Various versions of the VMF Exporter have unexpected orientation of models. This applies to the VMF Exporter that was part of the Wall Worm Displacement Tool and some versions of the exporter in Anvil.

The pre-Anvil exporter had several issues with model and proxy orientations. Then the orientation was fixed with Anvil... but the WWMT 1.771 update could create unexpected results with models and entirely incorrect results for proxies.

You should download WWMT 1.772+.

After installing 1.772, you may find that your models and proxies are flipped (180 degrees) on the Z-axis. This is because the rotation of models has been flipped 180 in the QC files in WWMT 1.771+ and in the accompanying VMF Exporter to make the orientation of models match their source rotation by default (which previously required you to use the "Flip" option in WWMT). Essentially, the default rotation and the Flip rotation have been swapped.

If you have models you compiled before installing WWMT 1.772 and the VMF Exporter is flipping your models, you will need to re-compile those models.