My white text becomes grey in exported mp4 file

[kayla_4941]

I'm editing a video and am using white caption overlays. They all appear white before I export them in the editing tab and preview. However, when I export it to a mp4 file, the file is "incompatible with QuickTime" and all my text overlay becomes gray like the pictures attached. The color grading of the video is fine, only the text colors are affected. How can I fix this? Thanks!

[Peru Bob]

How does the exported file look if you play it in VLC?

How does it look if you place the exported file on a timeline in Premiere Pro?

[kayla_4941]

It's still gray! The whole mp4 file itself is gray. It's also incompatible with Quicktime player which may be a problem... My last video exported perfectly fine and was compatible with QuickTime. The text was yellow though so maybe that made a difference. I think the whole video exported to be more saturated yellow as well. I'm really stuck! 

[R Neil Haugen]

What color space is your media, timeline/viewer, and export?

What is the graphics white set to ... hopefully, the 203 nits option?