Why dont my plants grow towards the middle/light and instead concentrate near the walls?

Well, if you didn't direct any growth there, how could it fill in? Need to train things out in that direction Can use the net to help spread the branches and hold them to grow vertically from that location.

Plants will grow up if light is present and they will twist and turn towards it in low light settings. In a grow tent the light is always bright so they are going to grow up. It looks to me like its just how the plants are growing and the centre of the pots, you can use some LST to thread them branches in towards the middle. Or rotating the pots is also a good idea, I find the hot spots the plants don't grow the most as its almost to bright. more intense lights makes the space between growth nodes shorter vs longer. so if the lights cool spots are on the sides it make sense they growing a bit more there vs in the centre. Good Luck!

Well it looks like you have three plants growing here so naturally there will be a space to fill in. The reason you want to instal as scrog net is to train your plant to fill the entire canopy and holes. This may take some time for them to grow enough to fill all the gaps. Just keep tucking as they grow through their stretch phase. Also, now is the time to cut anything below the canopy that is not getting adequate light. This will help with airflows and send more energy to the top canopy. Hope this helps.

They grow where you put them. If you put some buds inside the holes (e.g. the ones on the sides) you will hqavce no more holes :)