Files not properly closing in VBA editor

[Rijnsent]

Copied my post from reddit -

https://www.reddit.com/r/excel/comments/svfdng

I'm developing a model with lots of VBA (+XML menu) and a VSTO/COM add-in and bumped into something weird. The behaviour I saw: every second time I open my excel model, it crashes the Add-in. So open once, fine, open twice, error, open three times, fine, etc... The model & add-in interact upon start-up & upon close (commands getting fired from VBA to the add-in).

Upon digging deeper, I saw that the model I was opening was showing twice in the VBA Editor on those "even occasions", so 2 times with the same name. My hunch is that that's the culprit.

So what I did next:

• I switched off all my (COM) add-ins (so also my own) and made sure my excel has default settings.
• Next, I rebooted my PC.
• Start Excel, start new workbook (which shows up as Map1)
• Open the VBA-editor, see the file there too
• In Excel, through the menu -> file -> new empty file start a second workbook (Map2)
• Go to the VBA editor -> both files are there
• Close Map1 in excel (red cross top right)
• Go to VBA editor -> both Map1 & Map2 still show
• Start new files Map3, Map4, close them both
• VBA editor shows Map1,Map2,Map3,Map4... But only Map2 is open in Excel..

Does anyone have a clue what I can do to solve this?