This issue has been closed as 'Won't Fix' due to an extended period of time without updates. If this issue is important to you please let us know by posting on the AnswerHub or UDN, and Epic will re-open the ticket for further review.
When you import a Mesh with the import Materials / Import Textures checked ture from Max or Maya that has Opacity or an Opacity Mask set up on the model's material, the opacity settings and ignored on the Editor's created Material and any texture assigned in modeling software is not imported.
Also reproduced in Releases/4.8/Promoted-CL-2554075 & Main Promotable-CL-2554325
RESULTS: Both created Materials do not have Translucency
EXPECTED: Both Materials would have Translucency
Head over to the existing Questions & Answers thread and let us know what's up.