The competition between the four South African Super Rugby franchises and PRO14 teams from Ireland, Italy, Scotland and Wales was supposed to start this weekend.
Games for the South African sides were to be played against each other before they headed to Britain to play their other games within a bubble based in Bristol.
Issues around getting clearances to play from the British government saw the South Africans advised last week to suspend their visa applications.
Frustrations at several levels, chaos around travel bookings, and a lack of certainty as the situation kept changing have contributed to the unease.
Last week, a denial that the competition had been cancelled was issued. A fixture list for the first three rounds was released. But since then, the prospect has arisen that even the domestic games in South Africa may be cancelled.
Compounding the situation for the South African sides is the fact the competition was to provide them with warm-up games ahead of their contests with the British & Irish Lions in July where all games are likely to be held in either Johannesburg or Cape Town.
South Africa Rugby magazine said the one good thing about the situation was the most of the Springbok team was based overseas and getting match play ahead of the Lions tour.
"Still, there is a very real and massive financial impact to consider. SA Rugby, the franchises, players and coaches all took a financial blow through 2020. Players, coaches and management had to take pay cuts of up to 43 per cent, something they invariably could be looking at again due to the loss of income through television rights," the magazine said.
Options for an internal competition are limited as the franchises have already been involved in three successive tournaments. The magazine said there was not an appetite for yet another round of games.