First Byte missing for iPhone 8 iOS 13

[SBtest]

Hi,
I tried to execute test using iPhone 8 iOS 13, I got the response as well, but I can see first byte data is missing there. Can somebody suggest why is this so.
Test URL: https://webpagetest.org/result/200603_AP...57c9ec333/

One more query I have: When I use Moto g(gen 4/gen 6) with Firefox, I am not getting the performance data properly(first byte and #requests are missing). Even the waterfall is also not captured properly, While with chrome it working fine, any suggestions.
Test URL: https://webpagetest.org/result/200604_7W...6dab4f9b5/