I read the bug report, and if I understand correctly, this can be worked around. Just make the spidertron carry more robots than its personal roboports can activate. The fix says it prevents robots from carrying themselves , but not necessarily other construction robots. I would test it myself ...

yes I tried, it does not work in 2.0.28 due the bug fix
before the update it was all working fine. put ghost bots in the roboport and they will fly themselves to the roboport from the spidertron

this was working before 2.0.28 but it got removed after the update to fix a bug in https://forums.factorio.com/123638
i tried to let the inserter grab the bots from spidertron and put them into roboport, but this does not work neither (maybe only work on cars and tanks?)
now there is no way to ...

i am having the same problem. looks like it is caused by the update?

i tried to load my old save in 2.0.23 and it is working fine. the spidertron will fill the roboport with construction bot once you placed the ghost in map view.
in 2.0.28, even with all mods disabled, the spidertron will never ...