I've noticed that the autodocs in Lonesome Road don't cure addiction. This certainly happens with the ones in Hopeville and the Cave of Abbbadon, not sure if it's the case with all of them.
I've had this happen a few times with med-ex withdrawal, it wouldn't be cured in LR but was sorted out OK by the Sink autodoc. It's just a bit annoying, they fix body damage OK as normal.

Don't know if this affects any of the other DLCs, as I don't usually use addictive chems but I was using the Stealth suit in Lonesome Road and it kept giving me med-ex before battles.

I keep thinking I'll create a character that drinks and takes loads of chems, so far my characters have been very clean living.

It's specific to the Lonesome Road autodocs. If you look in the G.E.C.K., you'll see that they reused the Old World Blues autodoc but copied the wrong script. If you are on the PC I believe the Inofficial Patch fixes it.