Upgrading from Turbo belts to Advanced belts works fine, but trying to use the tool on Advanced belts does not work. An error is given in chat:
"Belts of type "extreme-belt" are not yet supported for tier-based upgrades. Please contact the Belt Thread Upgrades mod author."
Using the tool on an Elite belt works fine, though, to upgrade it to a Hyper one.
Sorry for the delay on this, I've been travelling. Turns out it was a mistake on my side, Krastorio 2 also has advanced belts (named as such) and I created a naming conflict. Which meant that it didn't know about the extreme belts, just the K2 equivalents. Anyway, fixed in 1.3.1.
Same thing goes for the new belt in planetaris-unbounded (https://mods.factorio.com/mod/planetaris-unbounded)
Compatibility added in 1.3.1.
