Hello! The look and feel of the cards between the new report canvas and the dashboard should be the same - but if you're using a report created in Power View in Excel you might see some changes. Sorry it's causing you to go and adjust them all manually! If you're using the Power BI Desktop, please make sure you've got the latest version and you should see the same visuals in both places.
Thanks for the reply, WillT. I believe it's the latest version of of Power BI that has changed all of my individual cards to become multi-row cards. This wouldn't be a problem for me if I could use multi-row cards to trigger alerts on the app, but it looks like currently only individually set cards are able to trigger mobile alerts. Are there any plans to change this in the future?