Run-time error '1004': Macro error, only when shared

Hey all,

I'm having an issue with my workbook. I manage a shared database that my office uses in our everyday operations. I recently upgraded a macro that

-Deletes conditional formatting for a range.
-Formats the range with real formatting (based on cell values).
-Copies and Pastes range into an e-mail.

This macro runs fine, except for when the file is shared. Sharing is necessary for our daily operations so it's not something I can work around.

When I try to execute the macro, while shared i receive

Run-time error '1004': Application-defined or object-defined error.

It will not let me debug this error because you cannot open VBA while shared. If I unshare the file, I do not receive the error.

Does anyone know what could be causing this? I know this is a very vague question, but I'm stuck here and as far as I can see... everything should work fine.

Attached is the workbook so you can see what the script is. The macro in question is "GSEmail".

Many thanks in advance!