Alarm ClearTime retains value null while th alarm is not active

Ignition
1

Ignition version : 8.1.29
Operating system : Linux | amd64
Java Version : 11.0.18+10-LTS

Problem encountered
Our customer complained about alarms in the alarmlist that remained in the alarmlist while the alarm was not present anymore

example
image

  1. KLA07 has a tag 'defect' with one configured alarm :

    Untitled
    Untitled739×814 44.6 KB

  2. Alarm settings :
    the alarm is active when defect has the value : 1

    image
    image969×478 42.3 KB

  3. the AckTime was > ActiveTime, the value was 0, but the clear time was still 'null'
    Untitled

Question
Has anyone seen such behaviour, and could this be a bug
could it be that the the clearing event was missed by the system?

How we temoprarily removed the alarms
To remove the alarms we had to resort to invers the setpoint (equal to 0) of the alarm to trigger the alarm, and then set the setpoint again to it's normal value (equal to 1) which resulted in the removal of the said alarm from the alarmlist