Sport change way too much my sims bodies

Hi! 

I play The Sims 4 on PC, I have all DLCs, and I have a bug when I make my sims do sport.

When I make them do sport, their bodies change way too much, at the point they look distorted like watching them in a distorted mirror. They lose almost all their hips, that get thinner than their tights. In the pics I join here, I show the same sim, in this order:

In everyday outfit pic 1-3 / In bathing outfit pic 4-6
When I started the game / When I made her start sport / After a few sessions (less than 10)

I play with mods but I don't use any that affects sports, fat and muscles, this happens since months even when don't use any mod. I have to go in CAS mode and give them their hips back for them to keep their natural body shape. At this point I don't even fix my game or uninstall and reinstall it anymore cuz I already did that many many times before for others bugs and it keeps happening. The things is that i feel it to be stronger with the time, the pics 3-4 and 5-6 are from only today. I started this game months ago but it's the very first generation, I didn't play that much with it before so the changes on her body are only today. 

Does this happen to you too? Did you fix it in any way? Do you know what I can do to get rif of this phenomenon?