After upgrading UIM to 23.4 CU5, UIM alarms stopped appearing in Spectrum.
Environment
DX UIM 23.4.5 uprgade
Spectrumgtw version 20.41
Cause
spectrumgtw - UIM - Spectrum version mismatch
Resolution
The issue was related to version incompatibility. According to the compatibility Matrix, UIM 23.4 CU3 (it's the latest listed in the current document), requires at least spectrumgtw 20.42 - however, together with UIM 23.4 CU5, a new version of spectrumgtw was released (23.4.5).
After upgrading the spectrumgtw probe to the latest version (23.4.5) the alarms started coming.