Yay, another issue. This app was installed pre-migration from the iX App Store, not from TrueCharts.
I had an instance of AdGuard home set up with the local certificate for my TrueNAS server. After migration to Electric Eel, the app would be stuck at “deploying”, but the actual app works. It did not matter if I had “Use HTTPS Probe” enabled or disabled. The WebUI port was set to 30004.
What I ended up doing to resolve this issue was to go into AdGuard Home → Settings → Encryption Settings and disabling the “Redirect to HTTPS automatically”. Once this was set along with “Use HTTPS Probe” disabled, TrueNAS Scale would provide the proper “Running” in the Apps list.