I'm having issues with conversations restarting after a (quick)load (the market guards repeatedly taking a break in mission 3, the 2 women and a coghead in Shadowing...) and being able to pick up (some) npcs (namely the caboose guard on the train in Shadowing...). However, convict.osm (and gen.osm for that matter are present) in both thief2 and thief2\t2x. Moreover, conversations are fine in stock T2 (tested noble and hammer in Shipping...and Receiving). Haven't noticed oddities in T2 FMs, either.
Any help is appreciated.convict.osm - 125,952 bytes
gen.osm - 429,568
$ md5sum convict.osm gen.osm
I remember conversations in T2X restarting if you loaded a save game made right after one had ended, so I don't think it's a problem with your installation.