I can't reproduce this with naturally generated bamboo or player-placed bamboo. In case you were referring to thatching, I also tested that without any issues either. Middle-clicking also doesn't appear to cause this issue with either. Please test again with the latest version of BoP and Forge for 1.8 without any other mods.

Closing this until it can be confirmed

Sorry for the delay in getting back to you - I was able to trivially reproduce this with the version of BOP I was using --1.8-3.0.0.1389 with forge 11.14.3.1543 (minecraft 1.8). I just put down some bamboo, then put a few on top of the ones touching dirt, then punched a few at random and one of them popped up looking like this:

Does this still occur on the latest version? It's likely we may have just fixed it unintentionally in builds made after the one you're using

Ah, okay, I think I know what you mean now - Sounds like it's a similar issue to saplings which I fixed yesterday

Yup, that was it, I can reproduce this now. As you said, it's about the age property being above 0. Fixing it now.

Should be fixed now. Let me know if there's any more issues. Apologies for my initial slow response, I haven't had the chance to look at BoP stuff properly until now.

Yes it does. I tried it with the 1.8.9-3.0.0.1603 version of BOP using forge 1.8.9-11.15.0.1684

What I did, in creative mode, is grab a bamboo and plant a bunch, stacking a few. Then I switched to survival and started punching the upper pieces (not the bottom one touching the dirt). Started getting some of those unknown blocks. Turned on F3-H and saw that they were bamboo but with a number following the item id.

Using F3 what I'm seeing is that the "age" of the bamboo is that 2nd number in the item number after the "/". As the mythbusters are often fond of saying "there's yer problem" :)