Thanks for the tag @thesmokingrunner 

Hi @memology ,

We are not aware of a limit on the watchlist.  It is possible there was an intermittent issue at the time you tried to add the item.  If you come across this issue again can you try refreshing the page and logging out and back in again to see if it then allowed the item to be added.

If it doesn't and you are experiencing the same issue can you let me know and provide the item number you tried to add along with the number of items you have reached on your watchlist. I will then have it followed up.

Thank you,

Kat