If you read the tags, it seems pretty self evident. I completed the weekly heroic today, and no engrams dropped.
English
#nvm
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They only drop at certain times.
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I'm pretty sure engrams are completely random and not a guarantee. Did you run it more than once? If you run multiple heroic strikes in a row you will have a better chance of getting more/better engrams.
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Oh also I did get the ten legendary marks, it might be a connectivity issue.