My timeline is still red after render

Hello everyone

I've been searching through thick and thin but I can't seem to find a solution, so now I'm gonna try my luck here.

I am currently editing some footage in PPRO CC 2018 (DSLR, 1080p 24fps sequence). I've slowed the clips down to 50% and with optical flow and a lot of the clips are nested and equipped with warp stabilizer.

When I need to render the timeline in its entirety (which takes about an hour) it stays red afterwards in a lot of sections of the timeline as if it completely forgot it had been rendering, and that means I have to spend yet another hour to re-render the timeline.

Has anybody experienced this before and if so, is there a reason why it won't render the timeline successfully? Is it a bug and if so can it be fixed?

Here's my specs:

Macbook Pro 15" mid-2015 (running macOS High Sierra)

2,2 GHz Intel Core i7

16 GB 1600 MHz DDR3

Intel Iris Pro 1536 MB

Premiere Pro CC 2018, 12.1.2 version

Thank you.