"Sdl.Desktop.Platform.CommandBars.IActionService" after plugin installation

Has anyone here using Trados 2022 encounter the error "Sdl.Desktop.Platform.CommandBars.IActionService" after installing independent plugins from the (private) RWS AppStore? In particular I've been struggling with installing WebLookup for days now, and despite trying several solutions (deleting the Plugin folders in Local and Roaming) the same error  appears on startup. 

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