Stumbled across this post when looking for a solution to fix column widths in a matrix visual. Seems this is still not supported, but we can vote for it at the PBI idea site:
Many thanks, Micheal. I voted and will also share with our community to vote for this feature.
This did not work for me as well. Could this be because I'm using the on-premise version of Power BI (August 2018)?
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