I wondered about that having tried something very similar. Its worth noting that the Ex passage contains "--;" not merely "-;". If you simply search for ".-" the result in respect of this passage is interesting. It only finds the first dash not the second. It would appear for some reason that the second dash is invisible.
True full regex support in searches would be really nice for cases like this.
There seems to be an inconsistency when searching for ".- <FOLLOWED BY> <WITHIN 2 Words> .- " It finds examples where there is only one "-" in the verse.
In the KSVS if finds Ex 18:19 which contains "God-ward" and Deut 32:31 which contains "Meribah-Kadesh" In both cases there appear to be no other hyphens within the verse. Note that is this case it also finds them when using <WITHIN 1 Words>.
Searching in the ESVS also finds many single hyphen entries within the verse. Interestingly enough it misses "sons-in-law" in Gen 19:14 but finds Beer-lahai-roi in Gen 16:14.
It appears that in certain cases the hyphen is associated with only one part of the word and in others with both parts.