File explorer search does not work properly after 1903 update

Hi all, so after doing the 1903 update on one of our computers (from 1709), the File explorer search seems to be... to put it bluntly, basically broken.

At first, when searching something, depending on the string, the results would be either, about a quarter of the files there should be (it seemed to be ignoring specific extensions) or basically every file but what was searched for. I managed to workaround this issue by completely deactivating the indexing for the folder.

However, a second issue appeared. The search now seems to treat some strings as separate search operands. Here's an example: When I search "DE", I now properly get all the files with "DE" in their name. But if I search "DE45", the search returns completely empty. But if I search "DE 45" with a space, now I get the files with "DE45", no space, in their names. It as if the search was treating it as two separate terms.

Unfortunately, I can't replicate the issue on my own computer. Instead I myself have yet another issue. Certain strings are returning completely empty results. Specifically searching numbers seems to increase the problem (for example, 01 and 02 return empty but 03 gives me results). This problem is not present on the other computer.

So yeah, many problems here with the file explorer search. How can I start fixing this? And if there's a need for screenshots, I'll provide them if necessary.

- - - Updated - - -

Alright, so, here's what I've found since.

I can replicate the second issue perfectly on another computer. The file search is treating letters and numbers differently and I can only search letters and numbers if they are separated as two operands (i.e. "DE30" returns empty, "DE 30" returns the intended "DE30").

I seemingly can only replicate the issue if it's a known extension. If the system doesn't know the file type, it seems to act normal and finds the results correctly as a single string ("DE30" returns "DE30" as it should) (I say seems because I've tried a few settings on this computer before testing on a computer where it would be a known type).

Indexation breaks the search. Once the folder is indexed the search will start returning similar results instead of simply exact results. For example, if I search for "D02", I get a few of the intended results, followed by a bunch of similar results, with the rest of the intended results peppered through. If this is intended behavior, this is possibly one of the worst decisions ever made.

In short, when it's a known extension, if the folder is indexed the search results are not what I'm searching, and if it's not indexed, the search treats strings differently than it should. When it's not a known type, search is normal, though has difficulty with numbers.

So, what is even going on here and how do I fix this?