C SDK version 21.171.0 compile issues under Xcode / Swift Package

Hi,

I've been using the C SDK as a swift package in apps for a few years but after updating to 21.171.0 I'm finding that it's failing to compile with a series of errors similar to the following.

Macro 'FIT_MESG_NUM_FILE_ID' unavailable: structure not supported

Has anyone encountered this error before and know of a solution?

Thanks,

Amy