It looks like I can no longer do a find an replace in a formula.
Or do you mean the "Replace Values" option in Query Editor no longer works? Could you be more precisely with the issue?
I reproduced the same issue on the latest version of Power BI Desktop(2.42.4611.701 64-bit (January 2017)). I have reproduced this issue internally. And I will post the updates here if there is any feedback.
Search and replace functionality in the formula bar is not supported. There was a product bug that allowed customers to use search and replace form open source component we are using for editing but there were many issues with their implementation and it was never tested and supported. Power BI team will consider in the future adding this functionality.