The issue is that the sizes in the paper catalog somehow getting deleted after a while. If we tick "display pre-define media library" in paper catalog using CWS we are able to see all the papers in the papercatalog and we can then reassign the papersizes and everything is back to normal until next time the papersizes are gone.
It seems, that the issue only came up when custom media is in use. .

Another issue on the J200 server is that customize pape size is not visible in the driver when using paper catalog entries.
Actions taken so far:
We have tested several command work station versions (4 and 5) and the issue remains.

Thanks for your support
/Thorsten