Opened a support ticket, they sent me this and it worked for me:
1. download/ install Line 6 Updater 1.27:
http://line6.com/software/
IMPORTANT! On newer macOS versions, your computer may display a pop-up reading "Line 6 Updater.pkg can’t be opened because Apple cannot check it for malicious software." THIS IS NORMAL. Click "OK," and open the System Preferences utility. Click "Security & Privacy," and in the Allow apps downloaded from section, click "Open Anyway".
2. download the HX Stomp firmware file 3.60:
http://line6.com/software/
3. connect the HX Stomp via USB to your computer. Use another USB cable/ USB port. Don't connect to an USB hub.
4. power up the unit while holding the "page >" button (blank screen).
5. shut down all Line 6 software including HX Edit (!), or any programs that use audio, like DAWs, iTunes, Spotify, video games, etc.
6. launch Line 6 Updater only, do not log in, choose "offline mode" instead, then select "HX Stomp Unknown version". Choose the downloaded firmware file and reinstall v3.60.
7. perform a factory reset on the HX Stomp (will delete all user presets, IR's, globals): while holding FS2 and FS3 turn on HX Stomp. Wait for "Will reset Globals and restore stock Presets..." to appear and let go.