Weeping vines seem to get burned by Lava, flowing or not.
If you place a Weeping Vine within 1 block of a block of Lava, it will be destroyed within a second of it being placed.
This contradicts the original plan for materials found in the Nether (including Planks and Wood from the Nether) to not burn.
Please provide a small video with the debug screen enabled (hit the
F3
key) demonstrating the issue.