VBA itself isn't covered by the OOXML specification so we're extremely limited in what support we can provide. I suspect the problem you're seeing may be related to going from XLSX to XLSM because controls are normally preserved in files with macros but it's basically impossible to debug these files.
Is there a way to replace these ComboBoxes with data validation or something else ?
Issue #1148 was marked as a duplicate of this issue.
Issue #1160 was marked as a duplicate of this issue.