Thanks for your answer.
I made a few tests and I found out that this "bug" was present since the beginning of my game. So maybe it's not a bug indeed, only an odd feature.
Well, we will see soon if it is intended or not.
I have just finished the Roseway quests and while inside the Unreliable I notice that I can sprint despite the encumbered status (the encumbrance icon is visible). However when I go outside the ship I cannot sprint, like it shoud be. Any tips to get rid of this bug?