I was using the ShopBot at my makerspace (it's been a while since I've used it). I downloaded the latest Fusion 360 ShopBot (openSBP) post processor (ver 42961) from https://cam.autodesk.com/hsmposts

When I tried to run the ShopBot, it was acting very strange. The spindle would not turn on. If I continued (I removed the end mill), the z-position on the display changed by a couple inches without the z-axis physically moving. Then it seemed to move properly (but at the wrong z height) At the end I'd get an error "Not enough axes designated to update all locations..."

The ShopBot control software is v3.8.42 (running on Windows 10). When I go to create the post in Fusion, there's a property window in the dialog box. First property says "SB3 V3.6 or greater". I had this set to "yes" because I'm running v3.8. But I decided to set it to "No" just to see what happens. Now everything works fine.