I have exported animation to FBX format from blender. I am not able to change it to legacy type in the inspector in unity as you can see in the image below.
The animation type is actually set from the type of rig that is being applied to the model. By default, Unity will import everything as having Generic animations, rather than Legacy, Humanoid or None. You can’t alter this on a per animation basis, but rather it has to apply to every animation that was included with the model on import.
To change this setting, select your model in the project view, go to the rig tab in the inspect and select “Legacy” in the “Animation Type” dropdown list.
when that happens to me I go into debug mode ( that itty bitty drop down menu way up top right unext to the even smaller padlock icon) click on the animation and in debug mode you can change the animation type. I forget which is which but if yours says 2 change it to 1 and if it says 1 change it to 2.