Generally getting team sheets is not a problem although, admittedly, there is great variation in how efficient or swift teams are with their administration. I've experienced a few issues lately where sheets have to be submitted electronically due to COVID and some team secretaries have been IT averse. If you continue to have issues do as Anubis suggests and advise the league representative - presumably you have to forward the team sheets to someone so if you're unable to do so because you aren't getting them it will reflect on you first if you don't raise it as an issue.