It seems to work fine. I tried the following:

1. Run shell:startup to open the startup folder
2. Copy the PL/SQL Developer shortcut to this folder
3. Add a userid=username/password@database parameter to the shortcut
4. Restart the PC

This is on a Windows 10 PC. I tested this with both the 32 bit and 64 bit versions.

Can you confirm that this matches your scenario?

Marco Kalter
Allround Automations