have you tried
nokia = enabled to moto = disabled ?
and from enable to enable ?
in the scenario “HO from a5/3 disable to a5/3 enable”, what is the actual ciphering mode in the target cell ? does the MS stays in the a5/1, as it was in the previous cell, or does it move to a5/3 ?
Your problem (no HO from a5/3 bss to a5/1 bss) could be analyzed by checking the HO REQUEST and HO REQUIRED message, in which you should find info about the ciphering algo chosen by serving BSC and by the MSC. If only A5/3 is shown in these messages, then of course it won’t work.