jcdude70 wrote: …I bought a new MacBook Air and my photos are on a Seagate external drive, which has Time Machine turned on. The photos are mapped correctly, but they have been syncing with iCloud for hours with no progress. All that I see is the message "Restoring to iCloud..." Any thoughts on what I can do?
I'm not sure exactly what's goin on. The brand of the drive doesn't matter much, but is it Solid State or mechanical? How is the drive formatted? To avoid damaging the Photos Library an external drive must be formatted in either APFS format or Mac OS Extended (Journaled) format. The drive must be connected directly to the Mac by cable, not networked, clouded, NASed, etc. Additionally, the volume can not have had Time Machine on it since it was formatted. There have been so many problems with using incompatible drives that the newest macOSs won't even allow a Library on a non-Mac formatted drive to open, since there is a chance of damaging the Photos database. See this:
Move your Photos library to save space on your Mac - Apple Support
If this drive is in a an incompatible format, stop running Photos with it immediately! A Photos Library can sit on an incompatible drive, but running it may corrupt the database.
Is Time Machine on a volume by itself? Nothing else can be on a Time Machine volume. A single drive can have more than one volume.
Are you using iCloud Photos? Do you use Optimize? If you intend to move your MacAir around as a portable, the may be some problems with keeping an iCloud connected Photos Library on an external drive.
What macOS are you running?
Let us know this stuff, and then we might be able to help figure something out.