New Webmail unusable on Windows 10 - Time Warner Internet

This question is about "New Webmail unusable on Windows 10", with Time Warner Cable internet and apps. On Windows 10 Pro (1709 version), the new Spectrum webmail is such a mess that I cannot use it.

I have NO ICONS in the new Spectrum email! It is extremely difficult to navigate as I have no idea what "q" or "'", or "/" stand for and there are many other mystifying markers where the icons should be. I also have NO Inbox or most other folders listed on the left side. Plus, there is text on top of text. Plain text email does not display properly. My address book was NOT imported. All I have is emails in the inbox.

Spectrum support told me that ONLY Internet Explorer and Google Chrome browsers are supported and, as an after thought, he thought Firefox might be supported but no others like Vivaldi, Opera, or forks of Firefox like Pale Moon, Basilisk, etc. I have ZERO problems with TWC webmail on my default browser or the others I use. NONE of the SAME BROWSERS work with the new Spectrum webmail. Yet Spectrum support told me that the problems are with the browser makers NOT Spectrum which makes little sense. TWC can write software that works with all my browsers but Spectrum cannot?

New Webmail unusable on Windows 10?