Sk. Sarpis- and Oss. Carv

As reflexes of PIE *selp- "butter" Germanic, Greek, and
Sanskrit have, not surprisingly, salb-, elpo-, and sarp-,
whereas all of the Iranian reflexes, including Khotanese
tca:rba-, Pahlavi c^arp, Persian c^arb, Sogdian crp, and
Ossetic carv reflect a proto-indo-iranian *c^arp-.

Are there other examples of this irregular correspondence,
and what might its explanation be?

I don't know anything about Albanian or its sound changes,
but I see it has gjalpë as cognate. Is 'gj' the expected
outcome in Albanian of PIE *s in this position, and if not,
can gjalpë be grouped with the Iranian forms in reflecting
an original affricate?

David