Combine PDFs randomly stops working Acrobat Pro DC
Hi,
We've got an issue on one of our office machines where combine will just randomly stop working. It doesn't give any error message as to what the problem is, it just refuses to combine.
Example workflow
Multiple PDFs open (only 1-2 pages max per PDF, < 10 PDFs on average in total)
Create PDF -> Multiple Files -> Add open files -> pop up shows, select relevant PDFs, Add Files -> Nothing happens, see attached screen below.

'Combine button does nothing, 'X' closes combine window and I can view single PDFs again without issue.
Restart Acrobat and it'll combine again but then will randomly stop soon after. Doesn't make a difference if I try to combine going through file -> create. Also makes no difference if I try adding files rather than using open ones.
Have tried repair installation. On latest version (18.011.20055)
Windows machine running Windows 10
Hoping someone can help with this frustrating issue!