Trial of Sekhemas bug report and feedback

First I want to report a bug that's occuring in the hourglass trial in trials of Sekhemas. As I understand it, 5-10 seconds into the countdown a rare mob should spawn. Killing this rare mob will decrease the time remaining and another rare mob should spawn. Sometimes however, the rare mob doesn't spawn at all or they stop spawning after killing one or two of them. This happens in approx. one in four hourglass trials.

Second I want to give a really short feedback and that's just a general lack of variety (maps, monsters etc.) in the trials, which gets boring after farming the trials for a while.