Apple watch says storage is full, but I haven't installed anything!!

Hello everybody,

My apple watch claimed the storage was completely full, but I barely used any space! I limited photos to 25, have got no music on my watch and have barely installed any applications. I freed up 155 MB by removing one app.

From the screenshot below you can easily count that the applications do not add up to 5.1GB.

So apparently space is being used, falling out of this overview. Or otherwise the number that appears, is wrong.

Can anyone help me in correcting this? Would a solution be restoring from backup? Or will the backup also have the wrong number.

Many thanks!