Issues when building with cloud build

My app builds without any problem on my computer and runs fine on all my android devices, but when I install the cloud build the app just crashes on start.

I have created a plugin for adobe analytics where I extend the UnityPlayerActivity to override some methods that I called CustomActivity. When building from my pc no error occurs but when I use the cloud build the app crashes on start, with the following error:

E/AndroidRuntime(18526): FATAL EXCEPTION: main
E/AndroidRuntime(18526): Process: com.ABCmouse.VideoApp, PID: 18526
E/AndroidRuntime(18526): java.lang.RuntimeException: Unable to instantiate activ
ity ComponentInfo{com.ABCmouse.VideoApp/com.ABCmouse.VideoApp.CustomActivity}: j
ava.lang.ClassNotFoundException: Didn't find class "com.ABCmouse.VideoApp.Custom
Activity" on path: DexPathList[[zip file "/data/app/com.ABCmouse.VideoApp-1.apk"

I have an androidmanifest in the Plugins/Android/ folder that references the plugin. Is cloud build overriding this manifest with one of its own? Could this be why the cloud build won't work?

The cloud builds were working fine before I added the plugin.

Another, seperate issue, is when I try to add the keystore that I am using to the build. I add it on the keystore page, add all the correct passwords, but when I press save, it returns to the settings page and says it is still using the development keystore. When I go into android settings again and press the drop down menu, it only has the default development keystore and add credentials like before. This is a major issue as I cannot test IAPs without signing the app.

Any ideas on what might be causing these issues?