CacheMultiStoreWithVersion -> store.(*iavl.Store).GetImmutable(version) error: "version does not exist"

[quaisx]

I am running into a situation when the call is placed into CacheMultiStoreWithVersion during gRPC call. When hitting this line:

func (rs *Store) CacheMultiStoreWithVersion(version int64) (types.CacheMultiStore, error) {
	...
			cacheStore, err = store.(*iavl.Store).GetImmutable(version)
			// if we got error from loading a module store
			// we fetch commit info of this version
			// we use commit info to check if the store existed at this version or not
			if err != nil {

the returned error is "version does not exist".

When debugging the calls to "commit":

func (tree *MutableTree) saveFastNodeAdditions(batchCommmit bool) error {
	keysToSort := make([]string, 0)
	tree.unsavedFastNodeAdditions.Range(func(k, v interface{}) bool {
		keysToSort = append(keysToSort, k.(string))
		return true
	})
	sort.Strings(keysToSort)

	for _, key := range keysToSort {
		val, _ := tree.unsavedFastNodeAdditions.Load(key)
		if err := tree.ndb.SaveFastNode(val.(*fastnode.Node)); err != nil {
			return err
		}
		if batchCommmit {
			if err := tree.ndb.resetBatch(); err != nil {
				return err
			}
		}
	}
	return nil
}

tree.root does not get populated for empty tree.unsavedFastNodeAdditions. As a result the code below goes into this condition:

func (tree *MutableTree) SaveVersion() ([]byte, int64, error) {
	...
	if tree.root == nil {
		if err := tree.ndb.SaveEmptyRoot(version); err != nil {
			return nil, 0, err
		}
	} else {

ane tree.root remains nil. Obviously, when later calling *store.(iavl.Store).GetImmutable(version) an error message in returned.
This behaviour manifests with some modules but not with others.
When I query the bank balance it fails "someapp q bank balances <alias|address>".