So when I went to implement what Gordon has suggested here, I found it to be logical but a bit complex. So I am documenting it for the benefit of anyone that has run into the same problem here.
Just to sum up, I saved a back up copy of a course and then restored it. We are at about Moodle 3.5 at the time of publication here. And I had Taskchains that weren't available because the restored Taskchain dates were advanced based on the start date of the newly restored course. This, I assume, is because they had been closed to students in the course I had backed up. So any task I clicked on in a Taskchain showed something like:
So, if you read through the thread above, you'll note that there is this discrepancy between close dates under Edit settings and Edit tasks. Edit tasks wins out over Edit settings. Perhaps this will evolve with future versions. I am not aware of all of the issues. But, to stick with my problem, I expected the entire Taskchain to be available and was unable to set that in Edit settings. So I choose Edit tasks.
This permitted me to view the settings for the individual tasks in a chain. i I enter the first task using the Edit "individual" Chain as indicated below:
And you see, the individual tasks are unavailable on an individual basis even though the entire chain is available as a whole, if this makes sense to you. Compare above to below if it doesn't.
So I enter the settings for the first task and change the date for the first task.
Which makes this task available. But only this task. As seen here:
The problem is when you have a lot of tasks. I sometimes have up to 10 or 15 tasks in a chain and many Taskchains, let's say up to 40 or 50, adding up to hundreds of individual tasks in a single in a Moodle course. And based on the way Taskchain functions right now, you have to enter each task and repeat the process. So as Gordon explains in this thread, you can set a default for each chain by making a change to the first task on the chain and then apply it to the rest of the chain. The next images are an attempt to demonstrate this process which is really useful when you have many tasks in a chain and perhaps many Taskchains in a course. Here is what you do. Note that you are in the "Time restrictions" columns.
And when you press on "go," the end result is what you want. Each of the task gets set to the default which in this case is no date set for individual tasks. It means that in my restored course, the students can enter this particular chain and do all of the tasks in it. It also means that when I set start and stop dates in "Edit Chain", it will apply to each task in the chain.
I quite admire the incredible flexibility that Gordon had integrated into Taskchain here. However, I should say that, really, most of my time, as a pedagogue, is spent creating the individual files that go into a Taskchain. And I think of a Taskchain as a whole when creating each one which is, I suspect, and would hope, is the case of most teachers using this tool.
As a result, I would prefer that the Time Restrictions in "Edit Chain" apply to each task in the chain in a single change. This means that when you change the availability in "Edit Chain", it overrides what "Edit Tasks" might think for each individual task. It is, quite frankly, what I suspect how most teachers think about a Taskchain meaning that few teachers likely set individual tasks in a chain differently than the entire task. And if they want different tasks to have different settings, they create a new chain. If I am wrong here, then please speak up.
Sorry if this post is kind of complicated. But if you have run into the same issue that I have here, then I assume that it all makes sense. Thanks for reading. And thanks, Gordon, for helping to clarify the technical issues of this most useful tool that you have created and maintained so faithfully.
I use Hot Potatoes, the Michael Rottmeier hacks for Hot Potatoes, Quandry, Rhubarb, Sequitor, Moodle and Taskchain which I consider extremely powerful pedogogical tools when used in combination. They aren't the only thing I use as a Moodle user. But Taskchain brings that list of things above in a the most wonderful way. It is a lot of work to build pedogical content but my students benefit greatly. And Taskchain sets each set of learning objects, as named above, up so nicely. I worry Gordon about the day you might decide that you need to retire and move on to other things.
Note: the images in this post have been create using Snagit and the SnagIt editor.