I was following lesson 23 of the UE4 Blueprint Course where we add physics to the sphere player pawn and my sphere was falling through the floor. The tutor doesn’t seem to have this issue however I was running UE 4.25.3 and the tutor uses 4.20.x in this course. I am assuming there have been some updates since then that cause the collision of BSP brushes to be slightly different.
The solution was to highlight all the BSP brush objects and convert them into a static mesh as shown in Lesson 11 (Marble Run - Converting BSP to Static Mesh). Make sure you go into the static mesh editor by double clicking your new static mesh file in the content browser, scroll down to Collision Complexity in the Details panel on the right and choose Use Complex Collision As Simple.
Hope this helps others experiencing the same issue.