Hello everyone, I am not sure this helps but I think it might.
As far as have been able to determine this feature is simply NOT SUPPOSED TO WORK AT ALL ANY LONGER.
A bit obscure but it seems to be that Apple "replaced" the "bluetooth connect facility" for IPhone and/or iPad to iMac with the "Air Drop" service.
That is to say there is actually no longer any need for using bluetooth to "pair and connect your iPhone or iPad to your iMac" .
It seems that now we have to use "Air Drop" to cater for those requirements. Certainly if "Air Drop" is enabled on all devices I can easily move photos and files etc. around between them all. My reading and understanding might not be correct but currently I believe that "Air Drop" does in fact use Bluetooth to identify devices in range etc but then it uses "wifi" for the actual data transfers.
In addition and FYI, the options in "Air Drop" are VERY VERY MISLEADING, basically 3 choices, OFF (not ON at all lol !), or ONLY PEOPLE IN "CONTACTS" - BUT BUT BUT this rather indicates I have to list MYSELF to be in "contacts" - lol lol again !, or "ANYONE" which seems rather risky and a bit odd to me ?? To me it seems logical that all of "my" devices should be able to "Air Drop" to each other WITHOUT me being listed in my own "contacts" and without me allowing "ANYONE" to "Air Drop" stuff to my devices. BUT THAT IS NOT WHAT IT SAYS under the "Air Drop" options !! NONE of the three choices shown do actually indicate the ability to have "Air Drop" fully active and available but restricted and limited to being possible ONLY between MY devices. Maybe I am just reading it wrong ?
Anyhow if 'Air Drop" is fully ON and is option enabled on my iPhone and my iPad for "ANYONE" then all works OK.
ZERO marks to Apple in this case for their crappy explanations and lack of clarity and update/notifications on this stuff.
Hope the forum/questions continue until we get good clear answers. If all of my above is incorrect then my apologies in advance and I look forwards to further updates. Cheers.