Hello together,

I am just discovering a very new issue for me. Never i got something like this.
I was developing a tool for our companies associates for data entry. Every associate has his/her own file. This Excel file (.xlsm) contains only some very hidden sheets with info for comboboxes and for some calculation with charts. The user only gets a userform on opening the file with a blank sheet as background. The user then fills the fields in the userform and with a submit button the data will be send to a SharePoint list. This all is ok and runs perfect.
Now the issue. Some users had the problem that after some days using suddenly the file opens with the blank sheet only. No userform starts. After opening the file on my PC for check I discover same. Then I opened the VBA editor. All the modules are still in the project explorer visible but if I check for the code the code window remains empty. Means, the code disappeared and so the file is no more working.
Did someone ever discovered same or similar problem? The strange thing is, that it happens only for a handful of user. the most have no issues with the tool.
For any hint I would be very grateful.