Formatting Issues Excel 2016 when sharing with PC & Mac

In recent weeks we've been having more and more issues with the formatting being completely ignored on our workbook. It's font size & colour that gets messed up, particularly in comments. We use Excel 2016 and all our work lives on Dropbox so that we can both share the same files. For years the file has worked perfectly. Now when we open the workbook and begin typing, the font size and colour just changes randomly. For example, we have cells that are set to font size 10. As soon as we click in it to type (on either PC or Mac) it just changes to 12! Our comment boxes have always been set to Font size 16 and Bold. When I right-click to edit it, the font looks fine but as soon as I click in it, it changes to 12 Courier and no bold. If I double-click to highlight the word it shows the correct size & bold. It's just weird and is completely messed up. The same goes for cells where the font is red and bold. It just changes back to black and bold. I've tried changing it back again and again and it's fine until I click in the cell again to type. I've tried using copy and paste or Format Painter. I've even opened an old copy of that spreadsheet and tried copying a cell over. As soon as you click in the cell to edit, the formatting is lost.

I imagine it's something to do with the fact that we have to open and save it on a Mac computer as well as on my PC. Does anybody have any suggestions as to how to fix this? We can't afford to pay for Office 365 because it's yet another monthly fee (no matter how much MS try to push this) so we're hoping for a solution to fix what we have. Opening the file by double-clicking or opening it from within Excel makes no difference. As time goes by more and more columns are being affected by this strange phenomenon.

I'm on Windows 7 and the other computer is an up-to-date Mac.

Hoping someone can shed some light on this, thanks.

Hi, I'm not sure how as it's a huge (confidential) workbook with several worksheets. Do you have any suggestions?

Thanks for your help. I'm attaching a mini version of the spreadsheet. If you click and type in the Mama cell for example, which should always be red and bold, it will change to black. The same applies to the Design column or the comments by the Names.

That's really strange. It does it on both of our computers. Yes, I know we have a lot of conditional formatting. Every time we add new lines to the spreadsheet it creates a whole load of new rules. I do go in and sort them out occasionally but haven't had time recently.

I'm at a bit of a loss now. It's infuriating as it's changing it with every single bit of text we type in those columns, including the email one. Maybe it's only with Excel 2016?

Thank you anyway for your help. Maybe somebody out there with Excel 2016 can duplicate the problem?

That would be great, thank you very much!

Oh wow, so it must be isolated to our two computers then! It's really weird! It does it every single time I click and type something in those columns. It's a mystery that's for sure!

Thank you for looking into it for us.

Hi SeoulGal,

A mystery indeed.. I'm affraid finding the cause will need methodicly exclude causes one by one.
Since the problem occors on both OS it must be in the file itself or in the Excel setup on eighter PC or MAC, Since the standard Excel is optimized to work on both versions an has proven to work in the past

- Have a look at recently installed addins
- Disable all addins one by one to find if it stops happening
- Is there any VBA active that is stored eighter in the file or in the personal macro workbook
- Are there any other workbooks open (with vba or file specific addins) when it occurs.