If Mirroring tools aren't working for you this video is a simple work around to getting your UVs to mirror in Maya so you don't have to do it twice and you ensure you have the exact same UV layout for both sides.
You can support this content by going to my patreon and you can find the rig there too :)
Subscribing to my channel helps a lot too :)
https://www.patreon.com/TreVital
the rig is also on Gumroad:
https://gumroad.com/trevital
and if you'd like to connect you can find me on IG here:
https://www.instagram.com/told_by_3/