Are tandem ATGM’s broken?

I was using the Sturm-S (8.7 ATGM carrier) and I noticed that the tandem ATGM is broken. In once instance, I shot the turret cheek of a Maus and did nothing but got the ‘hit’ indicator message. In another instance, I shot a ferdinand with it and it clearly hit their casemate front on, but did no damage.

The regular atgm works fine, however. Am I severely unlucky or is it an issue?

Its just ATGMs doing ATGM things…

Probably

They are BROKEN as bad as the GAME!