I have same problem
actually we have a similar problem
Model: RouterBOARD 941-2nD
Firmware: 3.19, updated to 3.22
MikroTik RouterOS 6.25, updated to 6.28
wireless band: 2GHz-B/G/N
security profile: WPA2 PSK | AES CCM | Pre-shared key
My devices: android Samsung note 2/3 and Lenovo T410/420/430 are getting connected and in a few seconds are loosing connection.
What details would you need in order to identify if there is a problem on my side or a proble with the latest version of OS/Firmware.
it was working just fine with MikroTik RouterOS 6.25 and Firmware: 3.19