Try to open about:support page and click the Verify integrity button in the Places database section. It should produce a log, you can paste it here for analysis.

`> Task: checkIntegrity - Unable to fix corruption, places.sqlite will be replaced on next startup > Task: checkCoherence - The task queue was cleared by an error in another task. > Task: expire - The task queue was cleared by an error in another task. > Task: vacuum - The task queue was cleared by an error in another task. > Task: stats - The task queue was cleared by an error in another task. > Task: _refreshUI - The task queue was cleared by an error in another task.`

It appears that there is corruption. However, the error persists through restarts.

Is it possible that checking the integrity DID something that would cause it to fix upon restart? Out of curiosity, I closed and restarted Firefox and bookmarking is back, but I did nothing else in the meantime.