Why can't stellaris study in technology?

First of all, you should have a scientist. The scientist can't sail the research ship, but he must be in the research cabin. Which of the three study periods stops when no one is around.

Secondly, you have to have relevant scientific and technological output (including physics, society and engineering). If the research output of three research slots is 0, this type of research will stop.

Third, you must ensure that your research has not been stolen. For example, your research ship is reverse analyzing the wreckage of the fleet. At this time, your engineering research slot is temporarily at a standstill, and the research point is used to analyze the wreckage. Similarly, the establishment of diplomatic relations will temporarily occupy the social research slot, and other events will also occupy the physical research slot.