Photos app uploads photos to Recents, not their respective albums?

Hi all, so I've recently bought an iPhone for the first time and have to import all my photos from my previous Android device to my new iPhone. Since you can't just Bluetooth your photos to iPhone, I started doing this by going to the Photos app on my Mac and moving my photos there manually, in manually created albums, with iCloud sync turned on. Initially for the first 200 photos it worked fine. Photos started showing on my iPhone in the correct order and inside the correct albums. When I uploaded a second batch through the Mac Photos app, things didn't go so well. Here's an example:

I have a photo album on Mac called Venice. It currently has over 150 photos. On iCloud (the website), only three of those are in the actual album called Venice (they were from the original 200 that worked correctly). All the rest have ended up in Recents and not in the album. Same story for the iPhone. The only place they show in the correct album is on the Mac where the import took place. Why is this happening? I have now over 1000 photos in Recents, all of which assigned to albums in Mac Photos, none of them showing in these albums on the iCloud website or on my iPhone. I'm at my wits' end with this. Any help or pointers will be greatly appreciated.