Deleting locally stored iPhone photos after import to Photos on Mac

I synced my old iPhone 8 with a new MacBook Pro. I wanted to transfer all my iPhone photos (local, no iCloud enabled on any device) to free space on my iPhone, so I imported all my media into the Photos app on my Mac. I selected "Delete after import," however about 1,600 photos/videos (of 4,000) did not delete from my iPhone. Is there any way to remove this images (already imported) from my iPhone?

Also, there are 23 photos/videos that appear to have been imported, however every time I try to import these remaining images, Photos switches me from the iPhone tab to the Imports tab. When I return to the iPhone tab, the images still appear there and I can still click "Import All" which leads me back to the Imports tab. Any solution to importing/removing these files?