'Search' Filter behaving like 'Dropdown'

This morning I noticed I was having a problem displaying values in a Dropdown (I have >1K distinct values). Typically changing the filter type from Dropdown to Search Fixes this, I noticed however that when I attempted to change the filter from Dropdown to Search the filter continues to operate like a Dropdown.

I have tried:

  • Rescanned default field values
  • Opened the dashboard in Incognito
  • Deleted and re-added the filter from the original question
  • Created a brand new custom question and applied Search filter from the start

In all instances when I try to create a 'Search' filter the UI looks and behaves exactly like a Dropdown.

What version of Metabase? What database?

version 0.51.4.5. Database is PostgreSQL.

That's quite old. I asked because I've had problems with filters in 54 and had to revert to 53.
No idea what to suggest, I only use dropdowns in current work. They work as search with dropddown once more than 1000 items.