This functionality recently stopped working, and is still not working after updating to the latest version, v3.4.6796.15142. The message popup, "Locating connection..." just remains in the upper right corner of the environment, and its possible to have several of them pile up. If I manually select my current DB in the object explorer, the messages will go away.
It doesn't seem to matter whether I invoke the functionality from the toolbar button, right-clicking in the query editor, or from the SSMSBoost\Query\Open current DB in Object Explorer menu option.
Currently using SSMSBoost from within SSMS v17.6.
UPDATE: The functionality only seems to be broken until you manually select your current DB in the object explorer for the first time, and then it will begin working normally, so at least there is a workaround.