The wiki article
Southern Celestial Rotation poses the question:–
Q. How can two people on opposite sides of the earth in Australia and South Ameirca (sic) both see the same South Pole Stars simultaneously?
and answers as follows:–
A. Since those areas are many hours apart from each other, when it is night or dusk for one area it is likely day or dawn for the other. It is questioned whether it is the case that those observers see the same stars simultaneously. Due to the time difference it may be that they see the stars alternately.
Which South Pole stars are meant is not specified. There is also a link in the wiki article to a video by Kyle Adams making the claim that viewers in Australia and South America don't see the Southern Cross at the same time.
At present it's summer north of the Equator and winter south of it, so the nights are longer in South America and Australia. The stargazing program
Stellarium shows on this date, July 15th 2020, at 11:18 (UTC+01) the Southern Cross is visible from Ushaia, Argentina at about 25 degrees above the horizon in the south. At the same time, the Southern Cross is visible from Perth, Australia at about 60 degrees above the horizon in the south. The local times will be 07:18 (UTC-3) in Ushaia and 18:18 (UTC+8) in Perth. Sunset in Perth is 17:30 and sunrise in Ushaia is 9:47.
It looks like we have two possibilities: (a)
Stellarium is wrong (b) the wiki is wrong. They can't both be right.
Have we FE members living in or near these two locations who can tell us if the Southern Cross is visible at the time stated?