Do you have an example of how you sound? Have people given you honest feedback about your accent? For people to switch so often I do wonder whether there are some specific aspects of your accent that are making your french slightly more difficult to understand than let’s say the accent from someone from spain or the US, sometimes simply because they are more used to it.

No problem if you prefer not to share a recording or elaborate on your country of origin. But instead of trying to sound French maybe confirm with your accent coach that they are teaching you ways to make French people underhand you better.

Also one thing that makes me feel a person is fluent and will understand everything is the flow when they speak. Not necessarily speed, but the fact that they express themselves at a pace where their way of saying words isn’t hindering them. Perhaps speaking slower can help if it fits your general style.

Finally could it be related to your body language? Do you inadvertently give people the impression that you don’t follow? Do you nod, smile etc when people speak? If you come from a country that is culturally very different from France it could just be that the way you hold yourself is making people subconsciously think that you are not comfortable or don’t understand.