I have a workflow that starts with a 2013 Workflow and if office A is chosen, a 2010 Workflow A kicks off. That works fine. If office B is chosen, 2010 Workflow B is supposed to kick off but now I get a "failed on start" error. I had these both working at one time, but they have required changes over the months. The first workflow creates and updates 5 items in both lists (name, date, phone, email, manager name). That info is inserted fine, but the workflow immediately fails for Office B. I can't figure out what the difference is if Office A works fine.
Although there is not much detail about the error, as you have mentioned that the sub workflows have changed, can you try deleting the start a workflow action and reselect the office b workflow, if you have not already tried that. Also after the main workflow calls the sub workflow, can you go to the workflow status page click on the blue information icon and check the error log.
I started removing parts of the workflow and noticed when I changed the task to an email, it did not fail. So then I put the task back in and it still did not fail. So for some reason deleting my task and re-entering it in the first step of this workflow did the trick for me. I don't know why but I'll take it :) Thanks for your help.