The signal lines shouldn't be floating in at least two of those cases, however the issue persists.
Also, keep in mind a wire is a resistance,
You suggest that lines supplying PWM should start floating when I power up a unit that they are supplying? T
Phew ! something about some Arduino forum users that gets me going I tells ya.
More read, less type.
Consider it a challenge.
Should also make it clear, the 2.7 and 5A will hold -