I've just upgraded to the latest firmware-iwlwifi_20190114-1_all.deb and I can
confirm that the problem with bluetooth on the 8265 is now fixed so this bug
report can be closed from my point of view.
Thanks.
P.S. Incidentally, the e91976c0 firmware for the wifi I was using previously
also fixed all of the problems I was having with my wifi connection in earlier
versions - even to the extent I no longer needed to specify any special options
(mostly 11n_disable=1 and bt_coex_active=0 to attain a semi-reliable
connection). I'll commence testing with the newer 9f0a2d68 version included in
this release and make good on my threat to open a separate bug report if I run
into any further problems.