yes common,
can try this:
pull handle up to horizontal and give it a thump horizontally towards the car. - This has worked for some others but not in my experience.
or turning the key fully one way then fully the other can sometimes correct this. but again most times not.
Otherwise you need to pull down rear seats, pull off the boot trim, (use both hands either side of the middle, it will make nasty sounds as it comes away, try not to break or tear it).
Then you can see the mechanism, this needs some lubricant as can dry out. from memory there is metal rod that moves either horizontaly or vertically, (i can rememeber which but think horizontally) lubricate this and operate a few times. then should be ok.
Basically when the metal bar moves it only 'locks' into place when it has operated fully. If its dry it does not operate fully and therefore the mechanism does not lock in place.
My advice would be leave trim off or partialy off a while then lubricate again week later before replacing the trim properly.
operate the boot from time to time if you use it rarely.