Outlook View in Browser Ignores Default Browser and Opens IE When Office 365 Doesn't Even Support IE

I'm still having a related issue, specifically with the Smartsheet for outlook plug-in, the sign in times out frequently, but clicking 'log in' in outlook (2016) brings up a new window that I can't do anything with except close in IE and it says unsupported browser, so I then have to log into the desktop site and sign into the plug in there and then go back, super annoying. I went into my system settings and changed as many default programs as I could off of IE and to Edge or Chrome, and same issue. What is it pulling IE from?? They need to fix this and let it run off the system program choice, since them forcing IE is weird when it's going away essentially. This is the only thread I've found talking about this exact issue, but it must be more people having this issue.