For 10 seconds, SF multi-PV shows only 2 moves, but there are 3 legal

You can see from this screenshot SF didn't show , at least for 10 seconds, 7... Ke8

SCREENSHOT: imgur.com/a/5ryoWkA
POSITION: rnbq1b1r/ppp1pk1p/1n1p2p1/4P1N1/3P4/8/PPP2PPP/RNBQK2R b KQ - 1 7

I urge you, HAVE MULTI PV ACTIVATED AT LEAST 3 PVS in a lichess analysis window. copy paste that FEN into an analysis window in Lichess, and look it takes a while to get the 3rd Ke8 move.

I didn't make a study, because it would already have analysis, and thus it would defeat the purpose of recreating the bug.

That's probably because it shows Cloud analysis. So presumably someone else (maybe you?) ran a 2 PV analysis on the position and it got stored. Then when you ran a 3 PV analysis you computer takes a while to overtake the existing analysis and until then it will show the already existing deeper one. (just my guess)

Arguably that is a slight bug though it shouldn't be a huge deal. And it's not necessarily clear that the alternative of "discarding" the Cloud analysis and instead show a new shallower one is really preferable.