I can share my experiences on this. I find that when I load the file, if the hip on V4 is gone, it's best to just reload or REVERT immediately. I have not found the need to toggle the genitals On/Off switch, and usually the reload of the scene fixes it. However, if you don't check for V4 missing hip and then do some work and SAVE the scene, you've probably messed V4 up. You can reload and reload the scene ater that, and it won't matter. The only fix then is to do what AnAardvark says above.

Be aware that sometimes after the fix AnAardvark mentions is used, the hip comes in distorted. I find the Waist Width morph can be manipulated to "almost" fix this.

I've had this problem probably 100 times in the last year, and wish it could be fixed, but Daz calls it a Poser problem and Smith Micro calls it a third party figure issue.

Good luck