I note that on my Nova eNodeBs with BaiBS_QAFB_1.19.6.7.2 (or any other previous version that I have tried), the unit will not allow configuration of GERAN neighbours in Band 5.
I you configure a GERAN neighbour ARFCN in Band 5, the unit will accept the configuration, but then gives an RF alarm and will not transmit.
I speculate that this is a limitation imposed maybe by a physical limitation of the Network Listen port hardware in this band, but I still do not see why the unit should not allow the neighbour to be configured. If all SON and ANR functions are disabled, the NL port should be irrelevant anyway.
There seems to be a myth that the neighbour config does not matter for CSFB. Not only would this be a violation of 3GPP spec, it is also simply not true.
I have tried CSFB with a GERAN base station in band 8 - it works perfectly. And in band 5 (without the neighbour configured) in both MO and MT calls, depending somewhat on the UE, the call is prone to failure.
Posting here in the hopes maybe somebody can shed some light on the reason for this, or maybe even a workaround!