Adding on to what @ankitpatira said, it's best to do all your aligning and positioning in Power BI Desktop. Once you publish it onto the service, you can fine tune the positioning by using the X & Y positions, Width and Height properties of each visualization.
Thanks for the replies. With the bugs in zero dimension objects on the desktop version, I don't feel lconfident spending time on work that could be lost at any second, so I guess Power BI is on the back burner until they fix it.
Feel this feature is severely limiting the type of work possible in PowerBI.
For example, I have one single Dataset that informs multiple reports. Basically Report A was created in the Desktop app, and then when published this created both Report A and Dataset A within the PowerBI workspace in web. From Dataset A, I then create an additional Report B that is using the same dataset. These reports are separated out due to them going to vastly different audiences, and us not wanting to throw a report at someone with 40+ tabs. Simply for convenience and usability, Report B had to be created out from Dataset A.
Here's where the problems start. With Report B (which was created in the web view), several visual elements are just stuck on an inappropriate layer (either they're on top when they should be in the back or vice-versa). As the report engineer, I have no way to fix this outside of downloading the PowerBI report and then re-publishing it. However, because Report B has a different name from Report A (and thus Dataset A), re-publishing Report B after making these edits results in a new dataset (Dataset B) being added to the PowerBI workspace.
So now I have 2 identical datasets that each need to be maintained and updated instead of the one single Dataset A, essentially doubling the work on the report owner's plate regarding dataset upkeep. Again, this simple missing behavior is severely impacting our team's ability to use PowerBI for our ends; really want to see this addressed in the near future.
Have the same issue, someone already submitted an idea but no popularity for it...
OK. The work-around is to use the View -> "Selection Pane" window to organize the order of visuals in the service. Use the up and down arrows when selecting a visual to change the order. The top most on the list is the top most in relation to the other visuals. Hope this helps anyone requiring this functionality.