Behaviour of CoRegisterClassObject and PackagedCOM

Question

I'm trying to build my CommandPalette extension, which is a out-of-process COM server. However, my native extension fails getting picked up by CoCreateInstance in CmdPal, causing a null pointer on the CmdPal side, while C#-based alternative implementation did the job. I used Process Monitor and saw that CoRegisterClassObject failed to read HKCR/PackagedCom/ClassIndex/{CLSID}, yet it showed up in regedit and the permissions set correctly. I believe this error caused subsequent internal registration to fail. How can I correctly register my class factory in the native land?