I haven't seen this before and don't know what is going on but I would start to diagnose this by disabling the multiple third party add-ins you have running and see if that resolves it. If so, enable them one at a time and see if the problem returns.

Looking at your screenshot I can see at least three add-ins: KuTools, SA Languages and LightPDF.

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Andrew Lockton
Chrysalis Design, Melbourne Australia