I'd be interested in why this happened also. I am no expert and I also have a couple of giant timbers that have had varied success. First thing you will be asked is the zone you are in and the sun exposure =)

oh lol That might help. I am in zone 8 and it gets full sun

Overwatering is generally not a problem with bamboo unless you provide so much water that it is sitting in a puddle for days on end. If you have been having hot weather, it's possible that that shoot did not get enough water, died, and rotted. Even well-established bamboo put out shoots that abort. I have one right now that has been in the ground 8 years and has put up about half a dozen 2" diameter culms, and 3-4 similar size shoots that got no further than 6" tall. I doubt that there is anything unusual going on with your bamboo.

P.S.: I've seen bamboo rhizomes go under retaining walls and come up at the higher level of dirt behind the wall, and this might occur as much as 5-10' away from the wall or right next to it. Just so you know...

Thanks for the great info! I will keep an eye open for shoots popping up in my yard lol.