How searches can be different:

1) Match in "verse text" or "all text"
2) book selection the same?
3) restrictions the same?
4) Match case on or off, ignore diacritics or vowel points on or off, ignore whitespace differences on or off?
If those do all match, is there a difference in the project version on the different computers, has the one "odd" computer done a send/receive as recently as the others?
Another thought, maybe the "odd" user should reset their Paratext, by holding Shift when they start it. This can be helpful when something in Paratext does not seem to work right.
https://paratext.org/ufaqs/how-do-i-reset-paratext/