How are you doing it? 1-by-1 (as putting 1 player in a .ted, another one in a different .ted, etc.), or trying to put several players on just one .ted?
The weird thing is that this isn't really blocked, as I recently recovered 5-6 players using this method, unless they block specific players, which don't seem likely, as it would be stupid if someone made teams using those players when they were still avaiable normally inside the game and now they couldn't import those anymore. It has to be a bug or something like that, I don't think it is deliberate. And it doesn't have anything to do with the live update, but could be something with the lastest game updates or data packs since I don't think it happened before (at least not to me, I've recovered like 50 players and nothing happened before, now I was trying to recover 5-6 players and I got the bug a few times even though I eventually got it working somehow). Don't know what is wrong. I might try to get those 2 players you said here and see if it works for me.
Just for confirmation, it's these 2 below on the links below, right?
Rolando Blackburn PES 2020 Stats - Pro Evolution Soccer 2020 stats for Centre Forward R. Blackburn (67 rating).
www.pesmaster.com
Marcos Riquelme PES 2020 Stats - Pro Evolution Soccer 2020 stats for Centre Forward M. Riquelme (72 rating).
www.pesmaster.com