This week there were/are three schematic options available from Ada-1: the hand cannon, auto rifle and the sword. After choosing the hand cannon and completing it on my titan I lost the other two schematics as options from Ada. Then on my hunter, I was able to see all three schematics to begin with but after completing the first auto rifle schematic following the machine gun, I was only able to see the auto rifle schematic from Ada once I returned to her.
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This is a known issue Bungie is investigating.