Hmm,
I tried this first on 4.2.0.3,
Having my IAP103 on channel 36 at first then removed all allowed channels except for 48 and it changed instantly (due to flag invalid channel). This method with removing current channel and adding another one worked several times to force a channel change.
2016-11-03 09:40:10 36 48 21 21 INV
However, when upgrading to 4.3.0.0 things did not behave the same.
My AP came up on channel 116, I then removed all channels from allowed channels except for 40. It then changed to 40 as excepted (not with the INV-flag but with P- ?!). Removing channel 40 and adding channel 100 did not trigged a channel change on the IAP.
I did a reboot and the IAP came up with channel 100. Removing channel 100 and adding 40 it changed once again with P- flag (which is odd), but after that i can't change channel until a reboot.