The latest version of Hexagon does have various issues. I would first suggest some steps to try to find where the problem lies.
1. If Hexagon has crashed, there is the possibility that the configuration file as become corrupted. So first, open Hexagon and “File-> User Resources-> Reset all”. Then restart Hexagon. (sometimes, even resetting Hexagon will not be enough, as the configuration file itself may required manually deleting. Hexagon does create a new config file on re-start).
2. There can be problems due to the OpenGL optimization. The setting for that is in “Edit-> Preference editor” -> “3D display-> Advanced-> OpenGL optimization”. Change the setting to “No optimization”
3. The next problem can come from attempting to export objects while there is dynamic geometry active (although that was supposed to be fixed. I have seen reports stating it can still cause issues)
So for example, after you create your tubing, before you export to .obj file, select the object then go to the lower right hand side window “Dynamic Geometry” and click on the little lightening bolt, which will collapse the DG.
If you do not use the dynamic geometry, you may be best, in the dynamic geometry window drop down settings, set it to “No DG”, so you do not forget to collapse the DG.