Custom themes do not sync across clients

Observed behaviour

The custom theme doesn't sync. Waiting longer or refreshing both clients also fail to get it to sync. Default themes are not affected and sync properly.

Reproduction steps

Open Fluxer on the downloadable client and web client
Make sure "Sync theme across clients" is enabled on both clients
Apply a custom theme to the downloaded client
Refresh the other client.
(Optional) Refresh both clients

Build information

canary build 609 (7d29f29), Electron 41.2.2, Windows 11 10.0.26200 (x64), desktop canary 0.0.122, locale en-US canary build 609 (7d29f29), Firefox 150.0, Windows NT 10.0 (x64), locale en-US

Platform

Windows

Evidence

I have enabled sync on both clients and applied a custom theme to the downloaded client before the video starts. I show the web client not syncing the custom theme even after a refresh. I then show that default themes are not affected and will sync properly

Details

Expected behaviour The custom theme should sync from the downloaded client to the web client