The only two browsers that I could find having the issue, were both BETA versions.

LOGIN PAGE PROBLEM
Chrome Desktop Version 57.0.2987.74 beta (64-bit), probably the developer edition also.
Firefox Mobile beta 52.0 (ARM)

NO LOGIN PAGE PROBLEM
desktop/windows10
Chrome Desktop Version 56.0.2924.87 release
Firefox Desktop 51.0.1 (64-bit)
Internet Explorer 11.0.15031
Microsoft Edge 40.15031

mobile/android7.1
Chrome Mobile 57.0.2987.74 beta (ARM), no problem with this mobile beta version.
Firefox Mobile 51.0.4 (ARM)

mobile/windows10
Microsoft Edge 40.15025

mobile/ios9.35
Safari (whatever is the latest version)


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