Although having to get a separate certificate for /M may make him like LoTW less...
In fact, you may have just hit upon the reason. My LOTW certificate is for HS0ZIB and I upload my logs using that contact. The fact that I am /M some 400 metres away from my base QTH should not require me to require a separate certificate. That's silly, (especially since LOTW awards do not recognise /M as a separate entity from the home call sign)
I have no idea if my contacts are uploading to LOTW with my call as HS0ZIB or HS0ZIB/M. LOTW would have to be failing me (and my contact) VERY badly if it fails to recognise that HS0ZIB and HS0ZIB/M are the same person, especially if the QSO falls within the correct time frame and operating band. (Actually, now reading N3QE's post seems to indicate that no contact has uploaded logs with the call HS0ZIB/M ...)
There seems to be no way to test this theory, other than by obtaining a second signed certificate for my /M suffix and then uploading all my /M logs again on the faint hope that some of these may match up, (and then I seem to have no way of deleting my incorrect logs that omit the /M suffix....
Suddenly, my interest in using LOTW has dropped - significantly
This kinda falls under the "well when did it last work and what did you change" category.
The last time it worked was for a QSO that I made 2 years ago where my contact specifically asked (via eQSL) for me to upload the QSO to LOTW. I uploaded that QSO about 5 months ago and the QSO matched up fine. Since that date ==> nada to every QSO that I uploaded
Simon, I had to get the second certificate for N5UD/M. I then linked the two. The problem appears to be the uploads. If I worked HS0XYZ while mobile, and he leaves off /M in his upload. I don't get a match. So I have to upload again as N5UD hoping for the match. The award credits all got to my main call N5UD.
In real practice, every QSO I have made since LOTW was started, has been from MOBILE.
It is really a big pain in the ---.
73 Tony N5UD /M