Hi Dek, my late 2011 plus 4 catch is also tight and like you the roof is rarely up.
It was up for a couple of days last week as I had read on here that it is recommended to leave the roof up to prevent shrinkage.
Anyway, it has been recommended that pushing down where the catches are whilst pulling the toggle makes it easier to release.
Or, adjusting the catches to be a bit looser gives a more reliable fix
Just don't made them too loose as the seal may not be good enough when it rains.
2011 Plus 4