blank menus, messages and dialogs in calc

I am trying to move from Office 2007 to LO on Win10. Most of the Office Excel spreadsheets move across OK. So far only one large .xlsm file is causing problems.

On loading the contents of the menus and system messages & dialogue boxes are all blank. If I change sheets. The menus etc become populated correctly. Even when returning to the original sheet. After a few interactions with the spreadsheet the problem recurrs. It can be solved by once again changing sheets.

The spreadsheet in question is rather large containing 11 worksheets and 2 dialog sheets and 14 macros plus a great deal of user data. The file size of the .xlsm is 1.2MB and when saved as a .ods 1.0MB, not clear why there should be such a large difference in size. The problem occurs in both the .xlsm & .ods versions.

Is this an issue with large/complex spreadsheets in Calc or is the issue elsewhere?

The answer to this question will help me decide if can move to LO or not.