Character and Platforms DISAPPEAR when pressing left arrow key? (And another issue)

Hello. I’ve been following a 2D side scroller tutorial on YouTuber from Alan Noon. I can near the end of the first episode, and I am unable to figure out what happened here. I have a few issues but the main one that is pressing is EVERY TIME I press the left key to get the character to move left, everything on the screen disappears. It reappears when I press right.

I figure it’s something in the HandleMovement function because when I adjust some things it doesn’t disappear, but I haven’t been able to figure out what is wrong! I changed barely anything.

The second issue is that my camera seems to just be stuck on the viewport and it’s really bothersome. Can anyone help me figure out what’s wrong here?

I have attached screenshots of my HandleMovement function and also my viewport.