Did you mark on your return that "someone else can claim me as a dependent on their return"? Is the reject code mentioning the 1095-A? Did your mom already file her taxes?
Go back to the personal info section and walk back through the steps making sure that you mark the box saying someone else is claiming you as a dependent. This will eliminate "your obligation" to have the 1095-A on your return.
Additionally, if your mom already submitted her return and you did not check this box, you would also be rejected due to someone else already claiming you.
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