This problem persists for a combination of Outlook 2013 and QB Premier 2020. I've been through the troubleshooting protocols at https://quickbooks.intuit.com/learn-support/en-us/feature-preferences/outlook-is-missing-in-quickboo... with my IT support, with a phone support tech from Intuit (no follow up on the management escalation of the ticket although they claim to have called me and left a message). I tried several times today through Chat support but the support got dropped when I had to reboot my system while following the steps.
I have heard someone say this is a "Known issue" and therefore insoluble but there is no documentation that the issue is insoluble, copious documentation that my combination of software should work and just recommendations for invasive and disruptive re-installation. I'm afraid there is something I'm missing and maybe the solution lies with Tools hub but I haven't hit the right combination of install steps and fix tools to make that button reappear (I did get it to work in Windows 7 previously for the same software version).
