Cant type subscriptions in Microsoft Office 365 Equation Editor

Question

Hi, I'm using Office 365, specifically Microsoft Word to type equations. I am used to the "_"/"^" shortcuts for subscripts and superscripts, respectively. Suddenly, these shortcuts stopped working. Now, when I type "A_0" for example, it stays this way and does not get converted to the proper format. These shortcuts still work in PowerPoint and Excel. I've tried reinstalling and repairing Office 365, but it still didn't help.

The Conversion ribbon is set to Unicode and the equation is set to show in professional format (not Linear). I access the documents by opening a Word application directly not through the Word for web. It's happening to all of my documents, not just one. The "Replace text as you type" option is checked in "File" > "Options" > "Proofing" > "AutoCorrect Options". Still to no avail. I also tried resetting the Equation Editor settings, didn't help either. I turned off all of the add-ins. there are no active add-ins running currently. still didn't work. It's such a weird problem. I've never come across anything like this.

I can insert subscripts manually from the Equation ribbon tab. The symbol shortcuts (e.g. \alpha, \sum...) work without any issues. Also, using the latest build, the LaTeX conversion doesn't work either. This does not bother me so much at this moment, but these issues may be related.

I've found three similar issues already reported, but the proposed solutions there didn't work for me.

https://answers.microsoft.com/en-us/msoffice/forum/msoffice_word-mso_mac-mso_mac2011/word-equations/6a5ad5f0-afc3-41e5-b6fe-5fdf84bc6d7d 

https://answers.microsoft.com/en-us/msoffice/forum/msoffice_word-mso_win10-mso_365hp/windows-equations-underscore-and-subscore/a7a775bf-fd65-4a2d-be11-0aa4a184d75e 

https://answers.microsoft.com/en-us/msoffice/forum/all/superscriptsubscript-shortcuts-in-professional/b03c38d2-67c1-4d98-bf51-6c92f0492449

I have already asked the same question in answers.microsoft.com (https://answers.microsoft.com/en-us/msoffice/forum/all/microsoft-office-365-equation-editor/c15b83ec-15de-425b-b351-924ac59117cb?messageId=f8c3077e-4143-4b9c-b377-c1cb37ffe1e1) and they referred me to Microsoft Q&A to solve this problem.

Thanks in advance.