I am happy to inform you that this issue has been nominated for implementation in the Mendix 6.6 release. If all goes as expected, it will be released at the end of May.
I believe this is a platform bug. I just saw this same issue with a client (he was planning to send me a test project so we could file a ticket) - it seems that any 0 value decimals are being written out to the OData service as:
instead of just
Excel doesn't like that, and I believe it's out of spec for OData to return data that way.
Can you file a ticket, and I'll do the same? Perhaps we can even get someone from R&D to chime in here.
use of toString(NumericValue) in a microflow where NumericValue = 0.00 will also gives 0E-8 ( Mx 6.4.1). So it is not only oData related