Should Pick data in a Collection be synced to the cloud?

Hi there. I searched these forums and didn't find any relevant information, so I'm posting my question. Please direct me to another thread if one exists. I'm sure my issue is not unique.

MacOS 15.3.2, LrC 14.2. iOS 18.4, iPadOS 18.4.

So, here's what's (not) happening:

Uploaded a bunch of images from my camera's card to LrC.

• Created a collection (in the upload module) inside a collection set so they will sync with the cloud.
• (I use collections as a rudimentary backup to complement my local backups. I rarely do any editing in the mobile apps, mostly cull when on the go, or show them to friends from my phone.)
• Simple cull by using Picks, in LrC. I don't remember whether I made the Picks in the catalog or in the LrC collection, but the LrC collection is showing the Picks.

A couple of days later, view this new collection using the mobile Lr app on an Apple device (either iPhone 16 Pro Max or iPad Pro gen 6). Filter by Picks.

• Filter by Picks, in the mobile app on either device, results in an error message: "No matching results. Try a different filter."

Should the Picks data be transferred to the cloud? What am I doing wrong?