This is one of those things that must have an obvious answer, so I'm probably being rash in using such a provocative subject line!
But anyway: it appears to be the case that many, many instances of "lak" (with long qametz = lamed preposition + 2nd singular suffix) at the end of the verse are incorrectly parsed as 2nd feminine forms when they are actually 2nd masculine in pause. These pausal forms are discussed in GKC § 29n. One example: Gen 14:21, where the antecedent is Abram but the "lak" is parsed as 2fs. In Jonah 4:4 "lak" is parsed 2fs; the antecendent is Jonah.
There are loads more -- 86 occurrences of these, in fact, although not all of them are wrong (Ruth, Esther, and SoS examples are correct). And BWks does find 25 examples of pausal "lak" correctly tagged as 2ms.
This is in BWks 9.0.12.627. Can someone explain this anomaly?
Update: I just checked for this with preposition bet, and they all look correct (see, e.g. 1 Sam 24:13, 14); so too with the direct object marker (e.g. Gen 6:18; Ezek 2:1). It's just with lamed that the problem comes (and it is the most frequent of these three cases where the phenomenon occurs).