My arcade is having similar problems. Games that previously submitted scores properly are now submitting 0 instead. The arcade has been running fine for years and nothing has been changed since the last update.

Are you using the vBSEO Rewrite-Rules?

Yes we are using VBSEO

If you are using this rewrite rules, try to remove this line from the custom rules:
We had the same problem with some games. After we removed this rewrite rule it worked very well.

I've tracked down the source of my problem. Hundreds of our gamedata folders have simply disappeared, no idea how. The arcade "thinks" those games are v2 now, which explains why they submit 0 when they worked ok before.