Summer grasses / All that remains / Of soldiers' dreams. - Basho.
There is a German transport that is tallied by a Russian fighter which is in turn tallied by a German fighter.
The German transport moves first.
The Russian fighter then moves next following its tally. But the Russian fighter flies up through some dense cloud that blocks LOS between it and the German fighter that has a tally on the Russian.
Does the German fighter immediately lose its tally on the Russian (and therefore does not move next because it lost its tally)?
Relevant rules section:7.2.1
Tallies are retained until:
(1) The target squadron is removed from the map.
(2) There is no line of sight to the target squadron in the Tally Phase.
(3) The target squadron is ten or more squares distant.
(4) The tallying squadron is broken.
(5) The tallying squadron drops the tally voluntarily during a Tally Phase. A squadron that drops a tally can attempt a new one in the same Tally Phase.
(6) The tallying squadron is attacked in air combat. If the tallying squadron is already in a dogfight, it keeps the tally on its current squadron, otherwise it now switches its tally to its attacker. Move the tally marker accordingly. If the squadron did not have a tally at all, it automatically places a tally marker on its attacker.
If a tally is lost or dropped, remove the tally marker from the map.
Based on this rules section, I would say the tally is retained until there is no line of sight in the Tally Phase.
In this particular case, the German would retain the tally and move immediately after the Russian fighter.
The designer might chime in to say yea/nay to this interpretation.