I called OTCM a few weeks ago to ask about how this can be possible. There seems to be some kind of agreement in place where the share counts are updated electronically — even for tickers extremely neglected.
As to why some get moved to Expert vs Pink I am of the opinion the primary driver is past SEC suspensions.
Now this is for CE stocks only. Still trying to figure out the rest. Could be that a Market Maker has requested they allow unsolicited quotes. If that’s it then there really is no way to predict what may or may not come forth.