Box 1 of Form 1065 Schedule K-1 should transfer to line 5 on Schedule 1, Part 1. Income from partnerships is reported on Schedule E, not Schedule C.
If a loss on Box 1 is not reporting on Schedule 1, line 5, you may have indicated during the K-1 entry that you did not actively participate in the business. That would make the loss "passive" and passive losses can only be used to offset passive income or carried forward to a future year.
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