Error when trying to add a term "La référence d'objet n'est pas définie à une instance d'un objet"

Hello everyone,

I use Studio 2019 and a problem appeared a few weeks ago. I cannot add terms to my termbases on the fly anymore.
Everytime I try Add term or Add quick term, whether using a shortcut or the mouse, I got an error message. I am not sure it is always the same.
I tried in several projects, with different termbases in different languages, the error keeps coming back.
Term recognition, however, works well, and I can add terms using Multiterm.

I do not remember changing anything to my set-up before the function stopped working.

Below is a copy the latest error message:

<SDLErrorDetails time="26/07/2019 11:54:50">
<ErrorMessage>La référence d'objet n'est pas définie à une instance d'un objet.</ErrorMessage>
<Exception>
<Type>System.NullReferenceException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</Type>
<HelpLink />
<Source>Sdl.MultiTerm.Core.Common</Source>
<HResult>-2147467261</HResult>
<StackTrace><![CDATA[ à Sdl.MultiTerm.Core.Common.DataContainers.TermbaseStatus..ctor(ITermbaseInfo info)
à Sdl.MultiTerm.Client.MiniEditor.MiniEditorControl..ctor(ITermbaseInfo activeTermbase, ITermHit activeTerm)
à Sdl.TranslationStudio.Editor.Terminology.TermbaseViewer.MultiTermViewerWinFormsUI.AddTerm(ITermbaseInfo termbaseInfo, String source, String target)
à Sdl.TranslationStudio.Editor.Terminology.TermbaseViewer.MultiTermViewerWinFormsUI.AddTerm(String source, String target)
à Sdl.TranslationStudio.Editor.Terminology.TermbaseViewer.TermBaseViewPartX.TerminologyProviderViewerAddTerm(String source, String target)
à Sdl.TranslationStudio.Editor.Terminology.TermbaseViewer.TermBaseViewPartX.AddTerm(ITerminologyProvider termbase, String source, String target)
à Sdl.TranslationStudio.Editor.Terminology.EditorTermbaseUtils.AddTerm(IEditorService editorService, ITranslatableDocument translatableDocument, String sourceText, String targetText)
à Sdl.TranslationStudio.Editor.Terminology.Actions.AbstractAddNewTermAction.AddTerm()
à Sdl.TranslationStudio.Editor.Terminology.Actions.AddNewTerm.Execute()
à Sdl.Desktop.Platform.Implementation.CommandBars.StaticAction.Execute()
à Sdl.Desktop.Platform.Implementation.CommandBars.ActionService.<>c__DisplayClass30_0.<ExecuteAction>b__0()
à Sdl.Desktop.Platform.Implementation.Services.Log.Resources(Object message, Action action)
à Sdl.Desktop.Platform.Implementation.CommandBars.ActionService.ExecuteAction(IAction action, ActionOrigin origin, Boolean allowToggle)
à Sdl.Desktop.Platform.WinForms.IgCommandBarAction.Execute()
à Sdl.Desktop.Platform.WinForms.IgCommandBarAction._lazyButtonTool_ToolClick(Object sender, ToolClickEventArgs e)
à Infragistics.Win.UltraWinToolbars.ToolBase.OnToolClick(ToolClickEventArgs e)
à Infragistics.Win.UltraWinToolbars.UltraToolbarsManager.OnToolClick(ToolClickEventArgs e)
à Infragistics.Win.UltraWinToolbars.UltraToolbarsManager.FireEvent(ToolbarEventIds id, EventArgs e)
à Infragistics.Win.UltraWinToolbars.ToolBase.OnToolClick()
à Infragistics.Win.UltraWinToolbars.ToolMenuItem.OnClick()
à Infragistics.Win.UltraWinToolbars.PopupMenuItemUIElement.DoClickProcessing(MouseEventArgs e)
à Infragistics.Win.UltraWinToolbars.PopupMenuItemUIElement.OnMouseUp(MouseEventArgs e)
à Infragistics.Win.TextUIElementBase.OnMouseUp(MouseEventArgs e)
à Infragistics.Win.ControlUIElementBase.ProcessMouseUpHelper(Object sender, MouseEventArgs e)
à Infragistics.Win.ControlUIElementBase.ProcessMouseUp(Object sender, MouseEventArgs e)
à Infragistics.Win.Utilities.ProcessEvent(Control control, ProcessEvent eventToProcess, EventArgs e)
à Infragistics.Win.UltraWinToolbars.PopupControlBase.OnMouseUp(MouseEventArgs e)
à System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
à System.Windows.Forms.Control.WndProc(Message& m)
à System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
à System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
à System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)]]></StackTrace>
</Exception>
<Environment>
<ProductName>SDL Trados Studio</ProductName>
<ProductVersion>15.0.0.0</ProductVersion>
<EntryAssemblyFileVersion>15.0.1.36320</EntryAssemblyFileVersion>
<OperatingSystem>Microsoft Windows 10 Professionnel</OperatingSystem>
<ServicePack>NULL</ServicePack>
<OperatingSystemLanguage>1036</OperatingSystemLanguage>
<CodePage>1252</CodePage>
<LoggedOnUser>AQUITRAD2-PC\USER</LoggedOnUser>
<DotNetFrameWork>4.0.30319.42000</DotNetFrameWork>
<ComputerName>AQUITRAD2-PC</ComputerName>
<ConnectedToNetwork>True</ConnectedToNetwork>
<PhysicalMemory>8255984 MB</PhysicalMemory>
</Environment>
</SDLErrorDetails>

I hope someone will be able to help (without having to uninstall and reinstall), because this is very annoying.

Thanks in advance!

Cindy