Seems like I can still use garages of my previous houses, if you press Y - request personal vehicle -view all you can see some vehicles that are in your previous properties's garages.
look here
https://imgur.com/2aIlgfZ
Here it shows only the current properties.
and here
https://imgur.com/McDtSYD
it shows also the previous properties
I don't know if it's already a known situation but this doesn't make sense at all.
Garages bug
That's correct, if you sell a property they are still technically stored there. It's not really an issue that will cause a problem for you. You can move them to a new garage by calling for them and storing them in another garage.
