Only Modal Utilities are truly modal on linux

Hi All,
Unity project was working fine before Easter break. Came back to it today and have a lock up issue. Unity starts up. The top bar works fine. However i can't interact with any other windows eg Hierarchy. My console reports "Only Modal Utilities are truly modal on Linux. System.Reflection.MethodBase:Invoke( object, object[] )"

Can anyone advise? Thanks.

Using mint 20 xfce, unity 2021.1.0f1. Everything worked a week ago.

 

Ok I've advanced some I think... I think it's to do with collab migration to plastic scm and trying to auto update. However I'm still totally stuck. I've added plastic to my repo's but have no idea how to advance. I can see manual migration advise but when I come to the "sudo apt-get install plasticscm-cloud" I get an error.

Code (csharp):

1.  
2. Reading package lists... Done
3. Building dependency tree      
4. Reading state information... Done
5. Some packages could not be installed. This may mean that you have
6. requested an impossible situation or if you are using the unstable
7. distribution that some required packages have not yet been created
8. or been moved out of Incoming.
9. The following information may help to resolve the situation:
10.  
11. The following packages have unmet dependencies.
12.  plasticscm-cloud : Depends: plasticscm-client-complete (= 11.0.16.6825) but it is not going to be installed
13. E: Unable to correct problems, you have held broken packages.
14.  

When I check what's available with "apt-cache search plasticscm" there's cloud available

Code (csharp):

1.  
2. apt-cache search plasticscm
3. plasticscm-certtools-mono4 - Certificate management tools modified to work
4. plasticscm-client-complete - A Software Configuration Management system from
5. plasticscm-client-core - A Software Configuration Management system from
6. plasticscm-client-gtk - A Software Configuration Management system from Codice Software
7. plasticscm-cloud - A Software Configuration Management system from
8. plasticscm-complete - A Software Configuration Management system from
9. plasticscm-dvcs - A Software Configuration Management system from
10. plasticscm-gnome-sharp-mono4 - Gnome-specific managed libraries to wrap the native ones.
11. plasticscm-gtk-sharp-mono4 - A content-aware merge tool by Codice Software, making easier for
12. plasticscm-libuv - libuv is a multi-platform support library with a focus on
13. plasticscm-mono4 - PlasticSCM Mono runtime
14. plasticscm-proxy-server - The Plastic SCM proxy server. Provides better performance results for heavily distributed teams.
15. plasticscm-server-complete - A Software Configuration Management system from
16. plasticscm-server-core - A Software Configuration Management system from
17. plasticscm-theme - A Software Configuration Management system from
18.  
19.  

Can any linux users advise what I need to install from this list? Thanks