Is something wrong with 'search' ?

Quick Search is just the Top Field in the Sidebar.

The rest of the Fields there are for an Advanced Search

I put "Isaac Fonteijn" (without Quotes) in the Search Box at the upper right - entering just that is Quick Search, and is what is shown, for reference, in the Field Labelled Quick Search in the Sidebar
It pulled up 9 results, including Isaac Fontijn - which seems to be the Profile you are describing

If in the added Fields in the sidebar (for an Advanced Search) I added 1854 for Birth (circa) it pulled up that profile and only that one.
It continued to pull him up if I added Leiden to Location under Birth.
If I then added Joseph F in Parent names, it failed to pull him up - and changed Joseph F to Joseph OR F
If instead I just added Joseph to Parent names, it pulled him up. Ditto if instead I just added Margaretha to Parent names
If I added Margaretha, Joseph - it changed it to Margaretha OR Joseph and pulled him up
Ditto if I just had a Space, no comma between the two

It seems if you enter two names in the Parent names Field, it claims it is looking for one OR the other, but it is looking for both
Margaretha Jack in parent names failed to pull him up - should have if really meant OR

Putting Meijer Frank in the Search Box in upper Right got 102 results.

If I went on from the Quick Search to do an Advanced Search by adding 1853 in Birth (circa), I got 4 results including Meijer Frank who was born in Meppel, Drenthe, Netherlands

If I then added Meppel in Location under Birth it then did not pull up anything - I think that is because Meppel, Drenthe, Netherlands is in the Place Name Field, nothing in the other Fields for Birth Location. Do not know which Field it is actually looking at there

ah, that might explain it. maybe...