So I'm not sure if anyone else has noticed but it seems alot of times when a rubber tree grows (may just be when placed with a MFR planter) it breaks the sapling, dropping it on the ground, and does not place a wood block where the sapling would go. [In this picture the planter has already replaced the airblock where the wood would be with a sapling] So.. Yeah. Would be great to see a solution for this, would mean making a rubber farm with MFR much more, well, possible
It's a bug with MFR itself, and unless sk or someone else wants to try and create a patch for it; It's not happening. Regardless, it's not an issue that needs to be fixed right away; So just replace the saplings with the wood and you'll be fine and it'll continue on its way.