You haven't yet uploaded an example DXF file as H S Rai suggested, however the most likely explanation is that the arrows are really there but they are just being displayed at a microscopic size (try zooming right in on the end of a dimension line to check).
The reason is that the current version of LibreCAD only allows one size of arrow per drawing. In other words individual dimensions can't each have their own individual settings.
You can set the global arrow size by selecting Current Drawing Preferences from the Edit menu and then selecting the Dimensions tab in the dialog box.
Yours drawings do NOT have dimensions, are LINES and INSERTS, and each block are LINES and TRACES.
The "problem" are:
TRACES are supported (open and read) but not draw. The "draw" feature was added in master branch after publised 2.0.8
You require to install "daily build" or wait to plublish 2.0.9 ( comming soon]