"Object reference not set to an instance of an object. (SqlManagerUI)"

Hi, I have this error message after adjusting some Securables on a Database Role and then trying to open Securables again. The same or others, makes no difference.
Using SSMS 19.1 via citrix published apps with RunAs.
I was able to open the Securables at first and added a table and stored procs but wasn't able to open it again to see if my changes were there. Got this error on every attempt, even on different DB connections or different roles.
After closing and restarting my SSMS I can see my result and adjust a role again. After clicking OK when done with my adjustments the window closes and after that the message appears again on every attempt.
Details:
Object reference not set to an instance of an object. (SqlMgmt)

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Program Location:

at Microsoft.SqlServer.Management.SqlMgmt.PermissionsData.Securable.GetImage(SecurableType type)
at Microsoft.SqlServer.Management.SqlMgmt.PermissionsSecurableSelector.InitializeBitmaps()
at Microsoft.SqlServer.Management.SqlMgmt.PermissionsSecurableSelector..ctor(IHelpProvider helpProvider, IServiceProvider serviceProvider, Principal principal, PermissionsDetailsGrid permissionsGrid, Object connectionInfo, Boolean yukonOrGreater)
at Microsoft.SqlServer.Management.SqlMgmt.PermissionsOfPrincipalsCore.InitializeSecurableSelector()
at Microsoft.SqlServer.Management.SqlMgmt.PermissionsOfPrincipalsCore..ctor(IHelpProvider helpProvider, IServiceProvider serviceProvider, Principal principal, Object connectionInfo, Boolean yukonOrGreater, Boolean showColumnPermissionsInDetailsGrid)
at Microsoft.SqlServer.Management.SqlMgmt.PermissionsDatabasePrincipal.InitializePermissionsCore()
at Microsoft.SqlServer.Management.SqlMgmt.PermissionsDatabasePrincipal.OnInitialization()
at Microsoft.SqlServer.Management.SqlMgmt.ViewSwitcherControlsManager.SetView(Int32 index, TreeNode node)
at Microsoft.SqlServer.Management.SqlMgmt.ViewSwitcherControlsManager.OnBeforeSelection(Object sender, TreeViewCancelEventArgs e)