Hi @NateOrr - multiple animations are supported, but the frame ranges must be set up manually when doing Edit Settings of the FBX file in the Asset Browser. In the Asset Browser, right-click on the file and select Edit Settings. Go to the Motions tab, and for your first motion, (re)name it what you like and press the “Add Modifier” button and select “Motion range”. Set the desired frame range for your first motion. Then press the “Add another motion” button at the top of the Motions tab and repeat this procedure, to add and define as many motions as you like from your FBX file.
If you have multiple characters in a single animation file, you will need to define different Actors in the Actors tab, and then make sure you have the correct root joint selected in the “Select root bone” field of the Motions for that character.
Please note also that any FBX file processed by the engine will have a .ASSETINFO file saved alongside it (same name as the FBX file but with the .ASSETINFO suffix) so that any information like the creation of multiple separate animations from a single FBX will be saved with the FBX - something to note if you are using any form of source control on your project.
I am not sure how you would expect FBX to “know” about your separate animations from your source file - is there a method in particular that you are using in your source file that you would expect to be translated into the FBX format and read by the game engine? Thank you for any more information you can give us - we are always trying to understand the needs of our customers and how to make Lumberyard better!