Empty site loading on BlackBerry 10 and Android 2.3 native browsers

[MLXProjects]

Hi, I'm testing Browservice on mobile devices (I know it's not the most supported hardware...) and for some reason, loading any site just gives a blank page without the address bar.
Pretty much the same as #96 but the workaround there (enabling bodyOverflowHiddenNotSupported via hex edit) didn't work either.

To give some context:

• I have a dedicated local server which just runs Browservice
• The proxy works on my laptop just fine, so hosting works
• URL changes with window ID, so browsing works - just rendering doesn't
• Browservice log shows nothing unusual nor different from visiting the same sites with my laptop
• Android 2.3 browser gives an empty but scrollable page which is almost twice the screen width/height (display size 240x320)
• BlackBerry 10 browser gives empty, non-scrollable page

I've tried with no flags, and setting things like --chromium-args=use-gl=disabled just in case.
My usual flags set user agent to get mobile sites and enable data dir, nothing else.

Any way to get more verbose logging, or anything useful at all given the mobile browsers don't have dev tools?