diff --git a/core/metadata/source.py b/core/metadata/source.py
index 65ac780c..fcd69569 100644
--- a/core/metadata/source.py
+++ b/core/metadata/source.py
@@ -1032,11 +1032,19 @@ def extract_source_metadata(context: dict, artist: dict, album_info: dict) -> di
         album_artists = album_ctx.get("artists", [])
         if album_artists:
             first_album_artist = album_artists[0]
-            if isinstance(first_album_artist, dict) and first_album_artist.get("name"):
-                raw_album_artist = first_album_artist["name"]
-            elif isinstance(first_album_artist, str) and first_album_artist:
-                raw_album_artist = first_album_artist
-            album_artists_for_collab = album_artists
+            if isinstance(first_album_artist, dict):
+                candidate = first_album_artist.get("name", "")
+            elif isinstance(first_album_artist, str):
+                candidate = first_album_artist
+            else:
+                candidate = ""
+            # An unresolved "Unknown Artist" placeholder from the album context
+            # must NOT clobber the real track artist already in raw_album_artist
+            # (bug #735: album-artist tag overwritten to "Unknown Artist" on
+            # import). Only override when the album context names a real artist.
+            if candidate and candidate != "Unknown Artist":
+                raw_album_artist = candidate
+                album_artists_for_collab = album_artists
 
     collab_mode = cfg.get("file_organization.collab_artist_mode", "first")
     if collab_mode == "first" and raw_album_artist:
diff --git a/tests/metadata/test_album_artist_unknown.py b/tests/metadata/test_album_artist_unknown.py
new file mode 100644
index 00000000..f8b96d93
--- /dev/null
+++ b/tests/metadata/test_album_artist_unknown.py
@@ -0,0 +1,73 @@
+"""Regression for #735 (CubeComming): importing media overwrites the
+album-artist tag ('Albuminterpret') to 'Unknown Artist'.
+
+When the metadata source resolves the track artist correctly (e.g. Billie
+Eilish) but the album CONTEXT comes back with an unresolved 'Unknown Artist'
+placeholder, extract_source_metadata used to take album_ctx['artists'][0]['name']
+unconditionally — clobbering the real album artist. The fix: an 'Unknown Artist'
+placeholder must not override a real artist.
+"""
+
+from __future__ import annotations
+
+from unittest.mock import MagicMock, patch
+
+
+def _cfg():
+    cfg = MagicMock()
+    cfg.get.side_effect = lambda key, default=None: {
+        "metadata_enhancement.enabled": True,
+        "metadata_enhancement.tags.write_multi_artist": False,
+        "metadata_enhancement.tags.feat_in_title": False,
+        "metadata_enhancement.tags.artist_separator": ", ",
+        "file_organization.collab_artist_mode": "first",
+    }.get(key, default)
+    return cfg
+
+
+def _extract(context, artist_dict, album_info=None):
+    from core.metadata import source as src
+    with patch.object(src, "get_config_manager", return_value=_cfg()):
+        return src.extract_source_metadata(context, artist_dict, album_info or {})
+
+
+def test_unknown_album_artist_placeholder_does_not_clobber_real_artist():
+    # Track resolves to a real artist; album context is an unresolved placeholder.
+    context = {
+        "original_search_result": {"title": "Therefore I Am", "artists": [{"name": "Billie Eilish"}]},
+        "album": {"artists": [{"name": "Unknown Artist"}]},
+        "source": "spotify",
+    }
+    md = _extract(context, {"name": "Billie Eilish"})
+    assert md["artist"] == "Billie Eilish"
+    assert md["album_artist"] == "Billie Eilish"  # NOT "Unknown Artist"
+
+
+def test_real_album_artist_still_overrides():
+    # A genuine album artist (not the placeholder) should still be used.
+    context = {
+        "original_search_result": {"title": "Song", "artists": [{"name": "Some Singer"}]},
+        "album": {"artists": [{"name": "Various Artists"}]},
+        "source": "spotify",
+    }
+    md = _extract(context, {"name": "Some Singer"})
+    assert md["album_artist"] == "Various Artists"
+
+
+def test_no_album_context_falls_back_to_track_artist():
+    context = {
+        "original_search_result": {"title": "Song", "artists": [{"name": "Solo Act"}]},
+        "source": "spotify",
+    }
+    md = _extract(context, {"name": "Solo Act"})
+    assert md["album_artist"] == "Solo Act"
+
+
+def test_empty_album_artist_does_not_clobber():
+    context = {
+        "original_search_result": {"title": "Song", "artists": [{"name": "Real Name"}]},
+        "album": {"artists": [{"name": ""}]},
+        "source": "spotify",
+    }
+    md = _extract(context, {"name": "Real Name"})
+    assert md["album_artist"] == "Real Name"