Then what you are seeing is likely not #7122 but what’s fixed in lib/model: Never send unpaused folder without index info by imsodin · Pull Request #7134 · syncthing/syncthing · GitHub (there were a few fixes based on @Alex’s reports in Device stays out of sync until restart - #25 by Andy)
That does not get resolved by a restart. Meaning the fix in v1.12.1 prevents the problem from occurring, but if it already occurred it wont get resolved. You’ll have to run with -reset-deltas on noda A for that. In hindsight it would have been good to do that automatically for everyone on upgrade to 1.12.1.