I'll start this post by mentioning that there's a general consensus that you should avoid columns in tabular data models that have both dates and times. That's largely because they don't compress well. However, sometimes you really do need to have both a date and a time in a single column.
For example, if you want to sort one column by the date and time, we have no option to sort one column by two other columns. And if you're going to create a composite column to get around that, you're really back in the same problem as storing a datetime anyway.
Displaying Values in a Table
But what really surprised me recently was that when I added a datetime column from my Live Query data model (source was Azure Analysis Services) into a table in Power BI, that the time values disappeared.
Only the date was shown.
I was quite puzzled about what was going on.
Why This Happens
Power BI has a limited range of data types. If you have a date, it's stored in a date data type. But if you have a datetime, it's also stored in a date data type.
So when you're designing a report, Power BI has to decide a default format for showing you a date data type element. And no major surprise, it just shows the date.
Fixing the Issue
To make the time values appear, you need to fix the issue back in the tabular data model, by adding a custom display format for the datetime column.
I can't say that I love this as a display format decision should really be made at the client application. I'm OK with the server supplying a default display format, but the client should be able to change it.
Unfortunately in Power BI today, you have no option to change the format of elements from Live Query data sources.
I hope that helps someone.