This has happened to me multiple times, usually at blue buff, where I place a shroom to help with blue but it doesn't place and I lose the charge. I'm not sure if it's happened with anything else or just blue buff. It also usually happens if I've already shroomed blue and the golem is already poisoned due to a shroom. Anyone else have this bug happen?

If you place the shroom too close to the aggroed camp it will attack the shroom immediately, possibly killing it or detonating it. Could this be what happened to you?