In Revit we can we can apply constraints (padlocks and EQ) using dimensions, which are very helpful in our modelling process. These constraining dimensions can be applied and then deleted, and even though they are no longer visible their constraints remain intact.
There is an important warning message box that appears that most users ignore.
If you read the dialog box carefully it tells you that even though the dimension is being deleted the elements will remain constrained. If you want to remove the constraints then hit the Unconstrain button in the bottom right corner. If you would like to keep the constraints then there is no point deleting the dimensions in the first place.
Reading the warning dialog may just save someone a bit of investigation work down the track.