Explorar challenge glitch

[IsaacDK503]

Someone else experienced a glitch with the explorer challenge? I was replaying missions to get a gold medal and I got "Explorer 8 completed" and also 9 after replaying another mission. I can't get 100% without it coming back one more time but I don't know what mission make this glitch happend, and I have no idea if they already patched it, if so, I will have to start again for 100%
There is only a video I can find about this and a Reddit post.

[Snackdubbzz]

The same thing just happened to me. I got the gold medal for the 2nd mission, "Enter, Pursued by a Memory" and unlocked Explorer 8 at the same time. This was the first mission I replayed since finishing the story. I'm going to reload an older save and try to complete the Explorer challenges before replaying any more missions.