If you have apps that publish complications, the data is cleared every time the watch is re-started.
This means that after a re-start, you have to go through all of your apps in turn for the complications to be updated so they are displayed, rather than just "--" being seen.
I see no reason why they should not persist as other application storage data is. I have been adding complications to my apps in order that they can be used by faceit and in folders and it's a real pain to have to go through each in order for this data to be displayed again.
