This change sucks (but as a long time Withings user doesn't affect me... for now), but I haven't had trouble with either the scale or BP cuff syncing to Apple Health. I don't have any suggestions besides double-checking the Withings app has permissions to write to HealthKit. I don't see any settings in the Withings app itself besides a prompt to check "Settings > Privacy > Health > Withings App".

Sorry if this isn't helpful.

Aside: all BP cuffs and their apps sorta seem to suck when it comes to sync. I also have an Omron. At least mine measure accurately. Make sure to validate yours with your GP.

I do appreciate your feedback, thanks. I just don’t worry about it anymore because I can just as easily say, “hey dingus, record a body weight/blood pressure reading of…”. I wish I’d figured that out after wasting time to get synch to work. :-)

... the process of validating the accuracy of my home BP monitor reminded me of the Physics 510 lab I did in graduate school!

Omrons do their primary job well but you run into the "IT is where great brands go to die" phenomenon that you run into everywhere -- like the stay I had at a Hilton where the staff was great but between bad wiring and bad React apps the IT experience was shoddy... Staff would be held accountable if they did a bad job but problems with IT are treated like the weather, something nobody can do anything about.