Bug in synchronisation

Hi all,

I been using lightroom for many years without any problem.  However lighroom now try to sync one photo   and it tries for many hours (more than 24h) without stopping. It succeeded in sync all my photo except one. I tried to see wich photo is the problem but when I use the "state of sync" filter, LR says that there no photo matching this filter. And it still indicate there one photo to sync.  I quit then restarted, same problem.  I have installed all the updates. The problem is still there...

Any advice?

Jean