I have been unable to find any tin ore.
I am flying in spectator mode with nightvision.
It is very very very rare or it doesn't generate at all.

It generates in mines in different chunks. I suggest using ore finding methods like OV/OD scanner for finding poor ores and ore mines

After more then 1 hours searching for tin ore in spectator mode, nothing to be found. If people have to find this in normal survival mode, that will be nearly imposseble. For now i will use an other tin ore generation mod. Closing this issue won't solve it by itself.

You can change the configuration for more frequent tin ore generation. Or turn on skygen in the configuration.