RB3011 packet loss on switch2 group

Strange thing, I was bothering with a problem with packet loss to some clients since I replaced RB493G with RB3011. Further investigation pointed me
to problem with ports on second SWITCH chip group.
Therer is substantial packet loss to connected devices 1-3% and only ond ports 6-10.
3011LOSS.jpg
In addition I realised that ports are flapping since reboot.

Had anyone encountered similar problem?

Ok, problem solved.
It was RSTP. after I disabled it packet loss is 0%.

Has this been resolved?