Automapper Stackoverflow exception with Entity Framework - domain-driven-design

Question

In our fairly complex DDD setup we have data models and domain models. Technically they are fairly similar with domain models usually having addition properties. We use Automapper to map between data and domain objects. The problem is that in some strange cases, on SaveAsync we are running into a Stackoverflow exception. Here is the code:
1) public virtual async Task SaveAsync(TDomain item)
2) {
3) TData data = null;
4) if (default(TID).Equals(item.ID))
5) {
6) data = mapper.Map<TData>(item);
7)
8) dataContext.Set<TData>().Add(data);
9) }
10) else
11) {
12) data = dataContext.Set<TData>().Single(x => x.ID.Equals(item.ID));
13) if (data == null)
14) throw new Exception($"Unable to find {typeof(TData)} with ID {item.ID} in the database.");
15)
16) mapper.Map(source: item, destination: data);
17) }
18) await dataContext.SaveChangesAsync(userIdentity.ID);
19)
20) // Update the IDs of the item and its children
21) var domainTest = mapper.Map<TDomain>(data);
22) mapper.Map(source: domainTest, destination: item);
23) }
As you can see on line 16, we are mapping to data from item without any problem. We added a test map on line 21 and that maps just fine. On line 22 is where the problem is SOMETIMES. In most cases this saves just fine and maps back to the TDomain item just fine... but when we try to save a change to an existing object that has a child that references the parent object we get this Stackoverflow exception.
I've been researching this for quite a while and I can see 2 options that could work: 1) add a MaxDepth to the config of this map so that this recursion goes only so far, but this feels very hacky and feels like I am masking the problem that could potentially become a maintenance nightmare some time in the future. The other option would be for the SaveAsync to return a new instance of the object (ie, line 21) this certainly feels way better than the MaxDepth way but still feels a bit hacky, like I am avoiding the real problem. Also, any values in the properties that exist only in the domain model would be wiped out this way. This would also be a fairly massive refactor affecting almost 20 apps, each having 5 to 20 saves... not that I'm complaining. Perhaps someone can point out what I can do to actually fix this problem or perhaps what I am missing here.
Just to be really clear, if you remove line 21 and replace line 22 with:
mapper.Map(source: data, destination: item);
You get the same Stackoverflow exception.

Answer 1

For now, I've added a bool is.... = true optional parameter to the save method, and I evaluate line 22 only if this param is true. In those cases where I go into this infinite recursion, I pass a false... I know this is really hacky so I am hoping someone responds with an actual solution... but this lets me keep going in my project