RAM preview not working for time lapse.

Hello,

I'm trying to have 2 time lapses (using images) in one 1080p video, but for some reason, the RAM preview won't work. When I mouse over a frame, I see what it looks like for about 2 seconds, then it goes black. I need to add text over the time lapse using handwriting and blend modes, so the RAM preview is important.

Thanks, Henry

16GB RAM

Intel i7 @ 3.6 Ghz (liquid cooled) (not overclocked)

Nvidia GeForce GTX 660 Ti x 3