troop glitch

i was playing game 502 and I placed a bunch of troops, about 20 I think, and started attacking and advancing them all. my troops advanced through about 5 regions and all the while 21 troops remained on iceland which i defo didnt have. at the end of my turn i went to shift those 20 troops and they disapeared.

didnt cause a problem in the end but i thought id mention it