{ANIMATIONS v2.8} ~ FBX exporting only the selected action rather than all of them (for Unity) MY ISSUE: when I export the mesh complete with its armature, only the currently selected action gets exported along in the FBX file.

I've rigged, skinned and animated a character.
Each animation is a separate "action", for a total of 4.

The scene includes 3 objects, which means 3 armatures.

The character's body armature is parented (as a "bone") to a rocking chair's armature, so to sync the movement.
Each armature is a separate object, but the movement of the character's armature is relative to that of the chair.

I export each of the three meshes (with relative armature) separately.
If exported singularly (by unticking the relative option), each action/animation works perfectly, in Unity.
If exported altogether, only the currently selected action/animation is exported; and works perfectly in Unity.

I've read threads reporting this issue being caused by keyframes linked to bones that no longer exist.
I've checked the "dope sheet" for lines entitled to non-existing bones, but all the keyframes are accounted for.

Is there something I'm overlooking?

This is my 3rd animation attempt, the first two working flawlessly.
In the first case it was a tree waving in the wind. All OK.
In the second case I added a walking cycle to a pre-existing blend scene. Exported with all the animations without a problem.
This time I got the character clean, so I handled all the stages, from rigging to animation.

In Blender everything works great and the animations look good.
When I export them, though, only the currently selected one gets exported.

Is there any way to know why all the actions other than the selected one are ignored during exportation?
Any log file?
When working under the Animation tab, select all with A  then when looking at the Action Editor, under Summary, you can see all bones that are being moved and or rotated for the selected action.

Here you need to make sure all names and bones are valid (Ie. nothing with red lines under it when you click the arrow beside the bone name). One this is complete you can open the Modeling tab and will want to select all meshes (using Shift + LMB/RMB) and use Ctrl + A and apply the scale.

Then within the Outliner, you will want to expand the armature, then Animation, then NLA Tracks, then expand each Action Stash. Then expand the Pose tab, and with selecting the bottom-most mesh you want to export, and Shift + LMB  the armature, it will select every mesh and anything within the Armature in the outliner.

Finally, go to File->Export->FBX, under Include go Selected Objects then Shift + LMB Armature, Mesh, and Other.

Under Transform, change Forward to Z Forward. Disable Add Leaf Bones under Armature, and lastly, disable Force Start/End Keying under Bake Animation (which should be checked).

With this, you can move to the desired output folder and click Export FBX.