Complex sentence: She made a few recordings which were not issued at the time (including a session with Frankie Trumbauer), thanks to surviving test pressings/masters the recordings were finally issued in the 1990s and 2000s.
Split into simpler sentences: She made a few recordings which were not issued at the time (including a session with Frankie Trumbauer). Thanks to surviving test pressings/masters, the recordings were finally issued in the 1990s and 2000s.