Null reference exception after install package using Unity 2019.2.5f1

So I installed Addressables 1.2.3 on Unity 2019.2.5f1 and as soon as I open the Addressables window under Assets Management I get the following null reference exception:

NullReferenceException: Object reference not set to an instance of an object
UnityEditor.AddressableAssets.Settings.AddressableAssetEntry.GatherAllAssets (System.Collections.Generic.List`1[T] assets, System.Boolean includeSelf, System.Boolean recurseAll, System.Boolean includeSubObjects, System.Func`2[T,TResult] entryFilter) (at Library/PackageCache/com.unity.addressables@1.2.3/Editor/Settings/AddressableAssetEntry.cs:532)
UnityEditor.AddressableAssets.GUI.AddressableAssetEntryTreeView.AddAndRecurseEntriesBuild (UnityEditor.AddressableAssets.Settings.AddressableAssetEntry entry, UnityEditor.AddressableAssets.GUI.AssetEntryTreeViewItem parent, System.Int32 depth) (at Library/PackageCache/com.unity.addressables@1.2.3/Editor/GUI/AddressableAssetsSettingsGroupTreeView.cs:248)
UnityEditor.AddressableAssets.GUI.AddressableAssetEntryTreeView.AddAndRecurseEntriesBuild (UnityEditor.AddressableAssets.Settings.AddressableAssetEntry entry, UnityEditor.AddressableAssets.GUI.AssetEntryTreeViewItem parent, System.Int32 depth) (at Library/PackageCache/com.unity.addressables@1.2.3/Editor/GUI/AddressableAssetsSettingsGroupTreeView.cs:253)
UnityEditor.AddressableAssets.GUI.AddressableAssetEntryTreeView.AddAndRecurseEntriesBuild (UnityEditor.AddressableAssets.Settings.AddressableAssetEntry entry, UnityEditor.AddressableAssets.GUI.AssetEntryTreeViewItem parent, System.Int32 depth) (at Library/PackageCache/com.unity.addressables@1.2.3/Editor/GUI/AddressableAssetsSettingsGroupTreeView.cs:253)
UnityEditor.AddressableAssets.GUI.AddressableAssetEntryTreeView.AddGroupChildrenBuild (UnityEditor.AddressableAssets.Settings.AddressableAssetGroup group, UnityEditor.IMGUI.Controls.TreeViewItem root) (at Library/PackageCache/com.unity.addressables@1.2.3/Editor/GUI/AddressableAssetsSettingsGroupTreeView.cs:238)
UnityEditor.AddressableAssets.GUI.AddressableAssetEntryTreeView.BuildRoot () (at Library/PackageCache/com.unity.addressables@1.2.3/Editor/GUI/AddressableAssetsSettingsGroupTreeView.cs:73)
UnityEditor.IMGUI.Controls.TreeView+TreeViewControlDataSource.FetchData () (at /Users/builduser/buildslave/unity/build/Editor/Mono/GUI/TreeView/TreeViewControl/TreeViewControlDataSource.cs:53)
UnityEditor.IMGUI.Controls.TreeViewDataSource.ReloadData () (at /Users/builduser/buildslave/unity/build/Editor/Mono/GUI/TreeView/TreeViewDataSource.cs:53)
UnityEditor.IMGUI.Controls.TreeView+TreeViewControlDataSource.ReloadData () (at /Users/builduser/buildslave/unity/build/Editor/Mono/GUI/TreeView/TreeViewControl/TreeViewControlDataSource.cs:25)
UnityEditor.IMGUI.Controls.TreeViewController.ReloadData () (at /Users/builduser/buildslave/unity/build/Editor/Mono/GUI/TreeView/TreeViewController.cs:288)
UnityEditor.IMGUI.Controls.TreeView.Reload () (at /Users/builduser/buildslave/unity/build/Editor/Mono/GUI/TreeView/TreeViewControl/TreeViewControl.cs:105)
UnityEditor.AddressableAssets.GUI.AddressableAssetsSettingsGroupEditor.OnGUI (UnityEngine.Rect pos) (at Library/PackageCache/com.unity.addressables@1.2.3/Editor/GUI/AddressableAssetsSettingsGroupEditor.cs:346)
UnityEditor.AddressableAssets.GUI.AddressableAssetsWindow.OnGUI () (at Library/PackageCache/com.unity.addressables@1.2.3/Editor/GUI/AddressableAssetsWindow.cs:135)
System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at <599589bf4ce248909b8a14cbe4a2034e>:0)
Rethrow as TargetInvocationException: Exception has been thrown by the target of an invocation.
System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at <599589bf4ce248909b8a14cbe4a2034e>:0)
System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) (at <599589bf4ce248909b8a14cbe4a2034e>:0)
UnityEditor.HostView.Invoke (System.String methodName, System.Object obj) (at /Users/builduser/buildslave/unity/build/Editor/Mono/HostView.cs:359)
UnityEditor.HostView.Invoke (System.String methodName) (at /Users/builduser/buildslave/unity/build/Editor/Mono/HostView.cs:353)
UnityEditor.HostView.InvokeOnGUI (UnityEngine.Rect onGUIPosition, UnityEngine.Rect viewRect) (at /Users/builduser/buildslave/unity/build/Editor/Mono/HostView.cs:329)
UnityEditor.DockArea.DrawView (UnityEngine.Rect viewRect, UnityEngine.Rect dockAreaRect, System.Boolean floatingWindow, System.Boolean isBottomTab) (at /Users/builduser/buildslave/unity/build/Editor/Mono/GUI/DockArea.cs:374)
UnityEditor.DockArea.OldOnGUI () (at /Users/builduser/buildslave/unity/build/Editor/Mono/GUI/DockArea.cs:341)
UnityEngine.UIElements.IMGUIContainer.DoOnGUI (UnityEngine.Event evt, UnityEngine.Matrix4x4 parentTransform, UnityEngine.Rect clippingRect, System.Boolean isComputingLayout, UnityEngine.Rect

May I have some help please

Edit: I get a blank Addressable window.

 

I solved this issue by downloading TextMesh Pro from the package manager instead of the asset store. It looks like there are conflicts between the packages.