I don't think the Search Handler for Showcase has been updated to handle Tags. Its a simple addition tho. Once implemented, you'll need to rebuild the search index for Showcase so that all the items get re indexed with Tags.
EDIT: The Showcase Search Handler has been updated.
Mod Security is known to cause a lot of problems if not configured properly. If you do a search on XenForo, you will read a lot of issues people have had (specially with the Admin CP functions).Mod Security
Try this. Create 2 NEW (Temp) showcase items. When creating them, add at least 2 tags to each one (the same tags). Then go to the Search Tags page and try a AND search based on 2 tags from those 2 items.
Don't be sorry, this is exactly what support is for The important part is that its working now!It’s working! Looks like the old files didn't get properly over written. When I uploaded the new files (SC 2.7.2), for some reason, FileZilla didn’t ask me if I would like to overwrite the Existing File. It just added it without replacing the old once. That said, I'm terribly sorry for the inconvenience. I promise next time I’ll be more careful when updating SC.
I cannot thank you enough for helping me.