Just as the title suggests, there is no build option to build the new Etherbugs.
The map needs to be Abandoned World: YES.
The tech requirement is Gold Storage: YES.
One of the following buildings: Mound, Glazed Mound or Unholy Mound of Worship: YES, YES, YES.
Etherbugs unlocked: NO.
Noticed it on a region I created a few days after v0.98.0 came out. Didn't notice it until now because I am kind of dumb and forgot why I wanted to play Abandoned World in the first place.
PS: When can I upgrade the Mound again without destroying it?
It's a know bug, about the bug race, at the next update we should be able to make the new bug.
:D
Just to confirm, the Etherbug can now be properly built in Abandoned World in 0.9.9 browser version.