Issue:When you want to dimension element beams manually IN the Viewport you need to double click in the Viewport and dimension in Model space, with a correct Dimension style.
Don’t forget to select the ‘’Add new entities to viewport group’’, when you are in the viewport.
View of the OPM when you double click in the viewport View of the OPM without selecting the Viewport.
When adding manual dimension, double click in the viewport.
Make sure the different viewports have different last Colum ticked.