Dear Y,
Good day!!
Apologies for the inconvenience caused and please don’t worry, let’s work together on your concern and move towards a resolution path.
I understand your concern and I would like to convey that I have tested the behavior at my end, where I am able to search with the same content on my List without any issue:
In this situation, I would like to request you to access the problematic List in the InPrivate or Incognito window of the browser and check the outcome.
If the same problem persists, I would like to confirm whether the same problem happens with the other users who are having access to the List.
If the other users are also having the same problem with the List, I would like to request you to perform the Reindex on the problematic List and check the outcome:
Open the List> Settings> List Settings> Advanced Settings> Scroll down to Reindex List> Select the check box and option “List content is missing from search results”> Reindex List> Wait for 24 hours and check the outcome.
If the same problem happens, can you please confirm whether the same problem happen with the other List in the SharePoint Online?
Appreciate your patience and understanding. Have a great day!!
Best Regards,
Sophia