Hello,
One way you have right. It seems to be OK on your hosting. have no idea why.
However I test few thing and one is interessant to me. If I am logged out from joomla SP builder account - I mean if I am using fake password, Blocks are loading correctly, fast, no problem at all, just I cant use them because not logged in.
When I insert correct credential, Block error 502.
So I have suspitious than you use other method for Block access authorisation than in Layout authorisation to your servers. Therefore Layout works fire. There is something different between blocks and layouts
Yes, this should be my hosting blocking, but because something is not good.
But why is it good on Blocks without sp builder credentials ?
Why Layouts have no problem ?