SU's cannot associate with the AP

I have an AP that will not associate with the 3 SU units. They were working for years without any issues but lately it seems to lose all the associations at times and right now they are not coming back. Currently all three SU are showing as power off on the AP. They are all fairly short distances with RSSI in range of -55 to -65dBm. A site survey from both ends shows little to no interference and all the channels are clear.

I only have remote access to the radios and can currently communicate to the AP. Everything on the AP looks fine: tx power, opmode, etc. The only issue is that now all 3 SU are showing as power off. A person on site confirmed all the SU are powered up and working. Up until today everything was working fine and no configuration changes or anything was done.

Would upgrading the AP from 2.0.7 to 3.0.1 be something to try? Would I also have to upgrade the SU to this new version or will it work if they are still on 2.0.7. If I did an firmware upgrade would it be possible to do a downgrade after?