You asked the purpose of gelling.
I am a geller. I like it because I like to be able to un mold the next day. It also has the benefit of making colors bolder/more vivid. If you are making confetti soap - meaning you shred some older soap and mix it with fresh soap batter - gelling the batch is helpful b/c it will melt the old soap a bit so it bonds better.
To avoid the spot in the middle, you need to either a) let to gel completely or b) stop gelling from beginning at all.
To get your soap to gel completely, soap warmer - I like my oils and my lye to be about 110. This not super precise. Wrap your soap in a towel, or even place the mold in a warmed oven. (Turn the oven off after you place the soap in it.) You will see a dark spot start in the middle that will gradually spread. You want to reach the entire log of soap, edge to edge, corner to corner.
To not gel at all - soap cooler. Is your mold a multi-log mold? My mold holds 4 logs. If I don't want to gel, I do not make 2 logs of soap side by side - I will use chambers 1 and 3, and leave chambers 2 and 4 empty. If you are making something like honey soap that really wants to gel, using individual molds can help because the heat can't build, like it builds in a log of soap.
The fragrances you are using may be a factor. Some fragrances (both FOs and EOs) are well-behaved, and some of them just want to overheat your soap.