Well, the 5th round of the Libertadores group stage has games from São Paulo (Talleres) and Botafogo (Universitario) on 5/16, a Thursday. This prevents the two Brazilian teams from playing in Series A on Saturday because there would be no mandatory 66-hour break.
As a result, São Paulo x Cruzeiro and Corinthians x Botafogo, for the 7th round of the Brazilian Championship, would have to be on 19/05, a Sunday. But the PM prevents games from the capital's big teams on the same day for security reasons.
The last round of the Libertadores group stage has the same conflict with the Brazilian Championship. On May 28th, Flamengo takes on Millonarios, and Botafogo takes on Junior Baranquilla.
Therefore, Flamengo and Botafogo could only play on Saturday, May 25th, to maintain the regular break. The problem is that, with that, it would be a classic (Botafogo x Fluminense) and a Flamengo game with Grêmio on the same day. Once again, Rio's security authorities prevent it to avoid fan conflicts.
The CBF realized the problem and left these four games with undefined dates, although the rest of the two rounds have already been scheduled. A solution to the problem is still being studied, possibly by relocating games from one of the two competitions.