July 2019. I fitted a pair of Bontrager XR2 Team Issue tubeless tyres on the mtb, combined with Barbeiri Anaconda tyre liners (aka builders foam backer roads aka pool noodles), and Caffelatex Tubeless Rim Strip (along with a couple of turns around the rim with tessa tape to seal the spoke drillings)
Now I probably didn't need the tyre liner things, however since it's converted non tubeless wheels I'm running, probably safer to have the tyre liners on to stop any burping! Absolutely zero issues since then! I'm only just this evening stripping them out, to put fresh sealant in!
Granted, I haven't done a lot of cycling on the MTB since then (due to health issues from July 2020 onwards...)