Fix REST API - Unable to Add FieldLink to ContentType
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I've already verified through MS Partner support about this issue, but it's yet to be fixed.
Gunjan Datta commented
I ended up writing a JSOM method as part of the gd-sprest helper lib.
Coming up to 3 years since I posted this, and not sure why it was never addressed.
I support this, it doesn't bring any glamour points to fix, but man is this an annoying bug! I cannot even use the workaround because I'm trying to do this from inside a Flow (Power Automate)...