You may see two manifestions when you try to extract utility from graphics when the source graphic is a Multi Line.

1. If you use the selection method, it will not allow you to pick a Multi Line
2. If you use a filter and the filter includes multi line in the filter criteria, you may get a crash.

The crash (#2) is in the pipeline for fix in a near maintenance release.  Both problems will be corrected in a future release enhancment by allowing Multi Line picking and filtering.

In the interim, the suggested workaround is to convert the multi lines to line strings and then pick/filter on the line string. Harry Stegeman has made a macro to assist in this process which you can review here:

https://communities.bentley.com/products/microstation/f/141/t/37024.aspx

You might consider a tweak to the macro to remove the line which deletes the original multiline.

After save the macro to your desired loocation, you can run it by the key in macro Path\chglines.bas.

If a fence or selection set is active then it will be used.  Otherwise, it goes into pick mode.

The results will be a linestring which matches the sylmbology of the original multi line.