Fix bug setting items in bytes MaskedColumn

astropy/table/column.py

@@ -1137,7 +1137,7 @@ def _encode_str(value):
         elif isinstance(value, bytes) or value is np.ma.masked:
             pass
         else:
-            arr = np.asarray(value)
+            arr = np.asanyarray(value)
             if arr.dtype.char == "U":
                 arr = np.char.encode(arr, encoding="utf-8")
                 if isinstance(value, np.ma.MaskedArray):

astropy/table/tests/test_masked.py

@@ -651,3 +651,10 @@ def __new__(cls, *args, **kwargs):
     # repr should need none (used to be 2!!)
     repr(c0)
     assert MyBaseColumn.counter == 2
+
+
+def test_set_masked_bytes_column():
+    mask = [True, False, True]
+    mc = MaskedColumn([b"a", b"b", b"c"], mask=mask)
+    mc[:] = mc
+    assert (mc.mask == mask).all()

docs/changes/table/15669.bugfix.rst

@@ -0,0 +1,4 @@
+Fix a Table bug when setting items (via slice or index list) in a ``bytes`` type
+``MaskedColumn`` would cause the column mask to be set to all ``False``. A common way to
+trigger this bug was reading a FITS file with masked string data and then sorting the
+table.