In space exploration I get a weird error where I can't place a lot of things on landfill. Can't place powerpoles, assemblers, powerpoles etc but substations, pipes, belt works for instance.

I get the error message "Cannot place on Landfill" In this pic I'm placing powerpoles right to left and when I get to the landfill I get the error. https://imgur.com/a/9Ss2Dcr

OK - that is an odd one. Can I ask you to do a test for me please? Check that this error happens with the following mod combination:

SE + TDOA + Transport Drones + Asphalt Roads
SE + Transport Drones + Asphalt Roads
SE + Asphalt Roads
SE + Transport Drones

Space exploration does some really funky things with tiles to try to divide space things from land things. It is possible that some interaction with roads is making stuff break.

Checked again. I have SE + Transport Drones + Asphalt Roads active and it works but as soon as I turn on TDOA I can't build half the stuff on landfill. The really weird part is that some things can be built so it's a strange bug.

OK - I will investigate. I've opened a github issue: https://github.com/drdozer/transport-drones-on-asphalt/issues/3

Appears fixed with latest releases of se and tdoa.