Outlook 365 messages will not download to PC

I have an odd one...  I use Office 365 online for business, and have a personal Office 365 account on my PC.  Occasionally, I want to send messages from the business email to my personal Inbox.  My personal email service provider is Spectrum. When I send messages from my business email to my personal email address, they appear in the Spectrum webmail Inbox, but do not download to my PC with Send/Receive (all other email downloads as expected).  This is a relatively new issue - what is going on?  Thanks.