New Rx Not Working

I recently received prescription modafinil through a telehealth provider. They are associated with a US licensed compounding pharmacy, who ships the medication monthly. The provider does not give you a copy of the prescription and requires using their pharmacy.

I’ve used moda previously with good results (the blister packs). With this prescription, however, it just doesn’t seem to work as well or as strong. Some days I take it and feel no effect.

Is it possible there is something wrong with the prescription / pills?