
Hi Peter_1985, it is a pleasure to be able to help you : )
For this issue, I tested locally. In my environment, my office version is 2016, I can reproduce similar situation that there is no response when editing a .xlsm file in app and pressing save.
Finally, I can solve the issue by pressing save as and then replacing the previous file in site.
You can try to see if this solution works in your environment.
Best Regards.
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