Working in V7 mode, after placing dimensions using a created dimension style, then saving and closing the file, the dimensions are dropped to elements when file is reopened (Note: when using 'None' as dimension style, this does not occur).
In V7 Workmode, anything that is specific to MicroStation V8 which does not have an exact structure previous to V8, it will be deconstructed to simple elements to appear the same. In this case, something is being used in the Dimension Style that is not compatible with V7 which is causing the Dimension to be dropped.
The Dimension Style Location setting 'Outside' is not available in V7.
Dimensions automatically dropping