Bug with gmt convert -qo?

I have a list of dates (in a file name dates.txt). So if I want to get the second value value I use
gmt convert dates.txt -qo1

When I run it on my pc with GMT6.2 (on Windows) it works fine.
But when I do it in the master version (6.3.0_d6ef2e9-dirty_2021.08.12 on Ubuntu) I get this error message:

gmtconvert [WARNING]: No data records provided

Should I use another module for this? Is this a bug?

Sample of dates.txt

04-2002
05-2002
08-2002
09-2002
10-2002
11-2002
12-2002
01-2003
02-2003
03-2003

Can’t you specify it directly when math is called to generate the file ? (otherwise awk -F[-] ‘{print $2}’ dates.txt) or something ?)

If I run gmt math it works:
gmt math Datos/GRCTellus.JPL.200204_202012.GLO.RL06M.MSCNv02CRI.nc?time = -fT -qo1

My questions is mainly why gmt convert stop working.

Hm, your input has no coordinates just trailing text (as far as gmt convert is concerned - the mm-yyyy is not an ISO timestamp). So it determines there is no data records. I don’t think that is right but that is what is going on. Most of gmt convert expects some sort of coordinates to act on.