Can't sync open tabs between two Macs or Mac >< Windows 10

Description of the issue:
Trying to set up Brave Sync for the first time, and while most features are syncing (theme, bookmarks, etc.), open tabs on one device are not syncing — but do appear in the History on the other computers in the chain.

Steps to Reproduce (add as many as necessary): 1. 2. 3.
(Self-explanatory)

Reproduces how often:
100%

Brave Version(See the About Brave page in the main menu):
Type of devices currently running on the Sync chain in question:
v1.42.88 on 2020 M1 MacBook Air (macOS 12.5)
v1.42.86 (updated today) on 2010 MacBook Pro (mac OS 10.13.6)
There’s a windows machine too, but I don’t have it handy

Additional Information:
I’ve read similar threads here in the community but they’re a couple years old, so I’m assuming this isn’t an ongoing issue that was never resolved.