Watch the temp in your room it looks really hot!! If you are using bought seeds, they should not become hermy. If this is the cas there are only three possible explanations. If the temp gets really high, with little difference between min and max the plants will react by producing male flowers. The second way would be erratic photoperiods (light/dark). If that changes daily by a large amount they will produce male flowers. The final reason is pure shitty luck. Generally female plants produce male flowers when they see their own imminent death, but 1/1000000 times they will do it because no male flowers are present, which is the case in every grow room. If your temp is above 35c alot of the time, change the room (add ac, blower, etc.) to lower the heat below 28c or forget it all together, they will almost always go hermy under these conditions.