Hello Amber,
Issue is occuring because your GW system is having SAP_GWFND SP13. Please apply below notes
Implement the following SAP Notes:
After applying the notes, clear the GW server by running transactions and reports:
/n/iwfnd/cache_cleanup (tcode)
/n/iwbep/cache_cleanup (tcode)
/ui5/invalidate_global_caches (report)
Once it is done, clear the browser cache too and reopen in new window.
You will get your catalogs back.
The above mentioned notes are already consolidated in 2251801 as mentioned by Krysta.
Hope this helps,
JC