LR now wants to resync all photos again

[#1]

I have a iPhone XS Max with over 20k photos/videos

I have previously seen LR report that it's sync is up to date.

However today I see it is auto-importing from the camera roll, with 19.5k pending.

What would cause LR to decide to reimport everything? What can it manage it terms of deltas?

I have added the odd couple of photos directly on the phone, and perhaps one or two on the mac for printing - since LR was awkward, but why would LR nw want to sync all.

Needless to say it's not good - hot phone whilst syncing, power drain, long elapsed time (days?). I'm starting to wonder if uninstalling LR is the only option

Any ideas?

[#2]

I have a iPhone XS Max with over 20k photos/videos

I have previously seen LR report that it's sync is up to date.

However today I see it is auto-importing from the camera roll, with 19.5k pending.

What would cause LR to decide to reimport everything? What can it manage it terms of deltas?

I have added the odd couple of photos directly on the phone, and perhaps one or two on the mac for printing - since LR was awkward, but why would LR nw want to sync all.

Needless to say it's not good - hot phone whilst syncing, power drain, long elapsed time (days?). I'm starting to wonder if uninstalling LR is the only option

Any ideas?