Limitation on number of FIT fields?

Hi,

I had an app working fine with 12 record fields and 16 session fields. The former started with an id of 0 and incrementing by one. The session fields started at 20 and incremented id from there. Adding one additional field to the session threw a "Failed invoking symbol" error.

I tried replacing the offending STRING line with a duplicate FLOAT entry with the same or different ID with the same outcome.  

Removing 2 session field creates worked fine with the new STRING field so the definition of this wasn't the problem. Note that the session ID's are no longer contiguous at this point but it works.

Using latest SDK. Simulating fenix 6x.

Is the a limit to the number of user fields? A bug?

Regards,
David