When I send a meeting invitation from my work computer (MS Exchange) to my personal (GMAIL) account, the invite does not get received correctly. In fact, it does not look like a meeting invite (in eM Client) at all. It looks like a regular email message, with no response indicators, meeting params, nothing. The meeting can be a one-on-one meeting or have multiple invitees, and it will still be formatted the same in eM Client.
How does the invite look when viewed using the web interface for GMail?
…like a normal meeting invite. I’ve attached two screen prints of the same meeting invite from my Exchange/Outlook email box - one is how it looks in GMail (mail.google.com web client) and the other is how it looks in eM Client. 
This has something to do with how my company has Exchange configured, because I tried it from another Exchange environment and the messages/invites were correctly formatted and I was able to respond in both gmail web and em client.
Best bet is if you have a Pro License, open a support ticket with eM Client. If it is something the application is not handling correctly, they should be able to pass it on to the developers and hopefully get it fixed.