Steps to Reproduce:

• Go to https://en.wiktionary.org/wiki/Special:UnconnectedPages
• Open the namespace dropdown

Actual Results:
Only the Wikidata-enabled namespaces are listed.

Expected Results:
There is a special item “all” on the top of the dropdown list to reset the namespace filtering, just like in Wikipedia.

This bug has probably connection with the fact that namespace 0 is not Wikidata-enabled on Wiktionaries.