I found an issue with S3D v.4 and am wondering if other users have experienced the same problem. I've searched the forums for other similar issues, but have found nothing. Hopefully this may help other users that experience the same issue.
Issue/bug; My Prusa I3mk2S printer would not set the extruder temp setting correctly when selecting "Print from SD card" in the printer after exporting the gcode file from S3D. The extruder setting would stay at 0 Celsius and not be correctly set whereas the bed temp would.
Solution: I saved a new/modified firmware settings file under Tools>Firmware Configuration>FFF tab. The changes I made before saving were deleting only the extruder "T#" command from the "Set extruder temp." line and the "Stabilize extruder temp" line. After Exporting, you have to select your newly saved profile in the process dialog box under the advanced settings "G-Code" tab > Firmware type box.
Conclusion: It seems that the Prusa Printer does not like the T# command very well, and this was the only way I could resolve the recurring problem. Maybe someone else has a different solution?