This is a known problem.  I had it happen to me dozens of times last year, and the block on posting lasted anywhere from 2 hours to 17 hours or longer.  I'm sad you're having the same frustrating problem.
Support Advocate Evan Lewis started talking with me about it in March 2025.  He's trying to make sure it gets figured out, but it hasn't been fixed yet.  

He recommends not making a Help Request if you have made 10+ posts in the previous 24 hours (you can post in the Computing Platform discussions instead) and not posting more than 60 comments per hour.  Doing either might cause the block on posting.

If you are willing to pass on information that might help them diagnose the problem, in the 4th comment of this other thread Evan Lewis lists the information he'd like; you can post the information about when it happened to you in that  other thread (preferably tagging Evan so he might see it). 

Good luck!
~ Janice, KA user

Thank you! I wasn't sure if this was a new problem or not, and that's too bad that it's been around for awhile.

Got it, thanks again!

I can do that. How do you tag Evan though? EDIT: never mind figured it out.