Hm, Play is blacklisted with you. Why? I don’t know. I just installed 6.1.5 here with me and ran it with Dorico 2.2.20 on Win and no problem here.
What if you open a command window and copy following text, then press Return:
“C:\Program Files\Steinberg\Dorico2\VSTAudioEngine\Components\vstscanner.exe” -p “C:\Program Files\Common Files\VST3\Play.vst3”
It should look something like this:
<?xml version="1.0" encoding="UTF-8"?>
C:\Program Files\Common Files\VST3\Play.vst3East Westhttp://www.soundsonline.comsupport@eastwestsounds.com16<?xml version="1.0" encoding="UTF-8"?>
ABCDEF019182FAEB2D45572D4577506C2147483647Audio Module ClassPlay2InstrumentEast WestPLAY_VERSION_STRINGVST 3.6.0ABCDEF011234ABCD2D45572D4577506C2147483647Component Controller ClassPlay2InstrumentEast WestPLAY_VERSION_STRINGVST 3.6.0
Also, what if you stop Dorico, delete the blacklist files and restart Dorico? That enforces a rescanning of the plugs. Does Play then turn up?