Pro Click button remaps & macros not working in Synapse on new PC (work fine on another laqptop)?

Device: Razer Pro Click (original, RZ01-02990), connected via the 2.4GHz USB dongle.

Problem:
On my HP PC (Windows 11), the mouse moves and clicks normally, but no button remaps or macros work at all in Synapse. The macros I created (next tab, previous tab, open link) show correctly in the Synapse app, but nothing happens when I press the buttons. The exact same mouse and dongle work perfectly on my ASUS laptop running Synapse 3 — all macros function there.

Key finding: It's not just macros — even a basic single-key remap fails. I assigned a button to type the letter "C", opened Notepad, pressed it, and nothing typed. So Synapse is not controlling the mouse on this PC at all.

Troubleshooting I have already done:

1. Confirmed Synapse is running and set to Run as administrator.
2. Re-created the macros fresh on the HP — no change.
3. Tested a plain single-key remap ("C") into Notepad — nothing types.
4. Checked Device Manager: no "Razer" device appears anywhere — the mouse only shows as a generic "HID-compliant mouse" (checked Mice and Human Interface Devices).
5. Ruled out software conflict from my Microsoft wireless keyboard+mouse combo (Microsoft Mouse and Keyboard Center is not installed/running).
6. Confirmed the physical switch on the mouse is set to 2.4GHz mode.
7. Tried different USB ports (direct to PC, not a hub) and moved the dongle away from the Microsoft receiver.
8. Confirmed Razer Synapse Service is running.
9. Did a full uninstall, reboot, and clean reinstall of Synapse.
10. On Synapse 3 (v3.11.228.12810) the mouse was not detected at all.
11. Synapse 3 then forced an update to Synapse 4 (said Synapse 3 is no longer supported).
12. After updating, the Pro Click now shows/detects in the Synapse 4 app — but remaps and macros still do not work over the 2.4GHz connection, and Device Manager still shows no Razer device.