Excel online conditional formatting ...can not use indirect formula

I have set up dependent dropdowns that expands with each new entry in a table.


This works on Excel Desktop, but if I attempt to add it to the same file in Excel online, I get an error "this entry leads to an error"

I attached this error in a screenshot. The odd part is that if I apply the conditional formatting on Excel desktop, and then upload the file ,and Open in Excel online. the dropdowns still work. I just can't set up or edit this conditional formatting in Excel online. Its an issue because I have to change / add / edit this type of formatting on new tabs on a live Excel online file being updated by multiple users, so downloading it, changing the conditional formatting and reuploading is not practical.

The formula I use for the conditional formatting is below, A12 is the cell with the first dropdown, and is the source table name and header name for the 2nd drop down


=INDIRECT(A12&"["&A12&"]")