What Jason said is right, this can happen that we "have matches that disappear at 1 level before reappearing at another"
Ian noted too that "If you don't have any matches beyond Y-12 and Y-25, then it's likely that either no-one in the FTDNA Y-DNA database is related to you via your male line within the last 1000 years or so, or you have an unusual number of mutations in your Y-DNA."
The issue he brings up "or you have an unusual number of mutations" is a real issue. It happens more often than we think that there are matches that appear at Y67 and Y111 that don't appear at Y37 or even Y25 or Y12.? It may be in yourself or in the "missing matches".
This is because the first 37 STR markers are a little more "jumpy" erratic than 38-67 or 68-111.? The additional markers tend to smooth things out for more refined matching. Here is a study about this phenomenon.
"The Strange Case of the Missing Y37 Match" related to the Owston surname concludes:
*** "Do not discount the possibility that match may exist at 67 markers but be absent at 37 markers." ***
"In analyzing the matches of 18 matching FTDNA Y-STR participants in the Owston/Ouston DNA study..
- 100% of the men who tested at 67 markers matched at least one individual who was not found in their 37-marker match list"
- "The percentage of non-matches at 37 within the 67-marker match list ranged from 3.6% to 35.3% of their total 67-marker matches.
- "An average of 14.1% of their 67-marker matches were absent from their 37-marker match list.
"The Strange Case of the Missing Y37 Match" Jim Owston, 2018
https://linealarboretum.blogspot.com/2018/02/the-strange-case-of-missing-y37-match.html
By the way, this happens with me. When my group first started with Big Y, four of my six Y111 matches did not appear at Y12, Y25 or Y37.? It turned out via Big Y testing that two of the four missing matches were related to me in the last 700 years, the other two in the last 1500 years. All four of these missing matches were instructive to me.
I encourage deeper testing, such as Big Y700, rather than relying on STR matching to build a tree.
