Apple Music library not syncing among all devices

My Apple Music library is not syncing among my devices. I have just three: an iMac (M1 processor), an iPad Air (also M1), and an iPhone 13. Sync Library is on with each device. Though I do have 84 playlists, which the iMac fully displays, the iPad Air and iPhone 13 list only 76.

All of the music in the library is purchased music through Apple's iTunes Store except for a handful that I recorded myself from LPs on a USB turntable twenty years ago.

Each device is running the latest system software: iMac—macOS Sequoia 15.3.1, iPad Air—iPadOS 18.3.1, and iPhone 13—iOS 18.3.1. Nothing seems amiss there. I've restarted each device at least twice, making certain of the settings on each. But nothing seems to change.

I'm up for any and all answers.