Yuris, YL2GM recently got in touch:
Very many direct QSL letters don’t reach their destination and are returned to me with the reason “address is undeliverable” or get lost in the process. I send out all direct QSL cards once every month. If you have not received your direct QSL card, please write an email to me and I will send again. (yl2gm@inbox.lv) Please also check that your address is correct in QRZ.com and Club Log. LoTW will be uploaded 1st of September.
this is problem with u.s. post office only. I do not know the reasons, but I have the same problems with sending mail to the USA. I think it is not necessary to print the callsign of the addressee on the envelope, it will be much better.I think that the callsign on the envelope is superfluous information and misleads the workers of post office.