intermittent search bug for Challenge winner in End Challenge modal

[Alys]

Rae / @rayonce14 (237eae03-eec1-4e47-a4d0-ac1e569c0866) reported a problem with the Username search in the "Select Member" drop-down in the "End Challenge modal. (That's the modal that you access by clicking on the red "End Challenge" button on the right-hand side of the Challenge's page, as opposed to the other two locations you can click on to see participants.)

The Challenge ID was b62848be-4f65-414e-be90-8e83b5915b8b (now closed). The Username being searched for was "362" (User ID ec560513-de7a-4ac1-870a-bd54134fe2ef).

When I searched in that Challenge for that Username, using Firefox 83.0 on Ubuntu 20.04, the search worked for me as normal. See the first screenshot below.

When Rae searched, over a period of a few days starting about 5 days ago, on Firefox 84.0.1 on a Mac OS running Catalina v10.15.7, the search didn't work. See the second screenshot below. Rae confirmed that there were no extra spaces at the start or end of the typed text.
Rae was able to successfully do searches for other Usernames on the same Challenge.

Then eventually about 2 days ago, Username 362 did work. Rae said:

I backed out and went back into the challenge just a moment ago and it brought up @362. I don't know what I did and I didn't clear my cache but it did work. I had a hunch to try it again because I clicked on this week's challenge (week 1) and searched for the challenge winner, got the same result (no name in the list), then accidentally re-clicked the search bar when I was trying to exit and it brought up the member's name. I did the same thing for 362 and it worked ("End Challenge"> "Select Member" type 362 --> no name, click on the white space, then reclick in the search bar space and @362 showed up in the dropdown list).