I think it got broken as part of the migration to a new system.
In the meantime, you can use an archive link such as
https://web.archive.org/web/20160701155 ... ms.io/lsp/
get to the category you want, and then delete everything before "https" to get updated results
for example:
1. click Samples
2. click Drums
3. cut out the part of the link you want, which would be: https://lmms.io/lsp/?action=browse&cate ... &sort=date