Mo. Rev. Stat. § 508.013
1. The provisions of sections 507.040, 507.050, 508.010, 508.012, and 537.762 shall apply to any action filed after February 13, 2019. A plaintiff who is a resident of Missouri and who has a case that:
(3) Has or had been set at any time prior to February 13, 2019, for a trial date beginning on or before August 28, 2019,
may continue to trial in the venue as filed.
2. For actions pending as of February 13, 2019, a plaintiff whose claim has been found to have no county in Missouri in which venue exists may proceed in such venue in Missouri where such claim was dismissed without prejudice only when the court finds that the claim:
(L. 2019 S.B. 7 §§1, 2)