My husband is diagnosed with Parkinson’s. Dementia also has spinal. Stenosis in his back. He gets around in wheelchair using feet when anyone pushes him he will pick up his feet when asked. Lately mostly after dinner I push him back to his room and he has trouble keeping feet up . Muscle tiredness or cognitive?
I agree the wheelchair foot plates should be on for any wheelchair travel, to avoid any foot/ankle injuries.
(Exception would be if travelling only a meter or so you could wheel backwards).
Can you adjust the footrest to be more comfortable for him to use?
What I do know is that I see this a lot, people not using the foot rest when someone is pushing the chair. This is an accident waiting to happen.
If you know you are going to be pushing him put the foot rest on and have him use them.
I can imagine after a long day he is tired and not being able to keep his feet elevated takes energy, concentration and muscle.
If the next day he can elevate his feet I would conclude that he was tired the night before.