Adobe Acrobat Reader dc unable to connect to my Gmail and other email account

In having searched online including this forum, I have as yet been able to figure out why (not unlike so many others) I have been unable to connect to my Gmail or another email account from Adobe Reader dc to attach and send a PDF file attachment using the send file by email menu item or icon. For whatever reason, whenever I try to sign in, I receive a display window stating 'Couldn't sign you in. This browser or app may be insecure' followed by the Adobe Reader message 'Authentication failed. Please verify your user name and password'. Believe me when I say I have tried virtually every suggestion I have read to date regarding this issue and nothing has worked to resolve this matter. Ironically, I have no problem opening my Gmail, Thunderbird, or server email account, attaching a PDF, and sending the email to the party intended as this works without fail each and every time. Ironically, I recall about 14 years ago using Acrobat (I believe version 6) that I was somehow able to use a method to open my then email account with a PDF file attachment already attached thereto from inside Acrobat and then send it without any issues whatsoever. While I resorted to sending PDFs over the last 10 plus years in opening my email account first and then selecting and attaching a PDF to the email, I would now prefer using the send email icon provided in Adobe reader dc to accomplish the same task. I should also state that I am by no means a newbie but rather one well versed in designing/developing interactive PDF forms in Acrobat Pro since 1993. After telling you this, you would think this should not be an issue but for whatever reason, I cannot seem to figure out the source of this problem and it's driving me nuts. If anyone on the forum has experienced and been able to solve this problem, to say I would appreciate knowing the solution is an understatement. Thank you ahead of time.