I've found it impossible to import directly from my iPhone to LrC. After a while it fails and the phone vanishes from the drive list.
ive resorted to LR cloud to make sure the only copy isn't on my phone.
searching around I see people having the same problem, and being recommended to use LR on their phone and let it sync to the cloud, then set LrC to sync those photos into LrC.
Are there any pitfalls in this method?
the main one I can see is that I will run out of cloud storage. I've seen indications that you can turn off the sync to the cloud which will leave the photos on my hard drive but delete them from the cloud.
That's the approach I take and it works great. Much better than trying to directly import. If you're worried about space in the cloud, simply remove the images you no longer need in Lightroom in the cloud from the all synced images collection and they will remain in Classic but get deleted from the cloud. I also set up the location for synced images to be the same as my standard normal import scheme in Classic so that phone images get synced into the same folders as DSLR images and end up neatly sorted by date.
Since the "import" functions built into the iOS and Android phones are terrible, for what little I take photos on my Android phone, I just manually copy the new images from the phone to the computer using the computer's file browser, then import into LR Classic from the local hard drive.
Turning on the sync from LrC will not add anything to the cloud. It will only download the images already in the cloud to a local drive. This is the easiest and most seamless way to move photos from a phone to your computer. I recommend setting up a custom location for the downloads. You find this option in preferences in the Sync tab. After the images are download you can delete them from the cloud. If you use Lightroom on your phone to delete the photos, they will delete from the cloud, but not LrC.