'NoneType' object has no attribute 'instance_offset'

[S1lander]

It seems to be working fine in a freshly created blender file, but when I try to use cad transform in an existing project I get this:

Traceback (most recent call last):
  File "C:\Users\silas\AppData\Roaming\Blender Foundation\Blender\4.0\scripts\addons\sl_ct\operators.py", line 2369, in invoke
    self.init(context, event)
  File "C:\Users\silas\AppData\Roaming\Blender Foundation\Blender\4.0\scripts\addons\sl_ct\operators.py", line 2350, in init
    self.init_handler(context, event)
  File "C:\Users\silas\AppData\Roaming\Blender Foundation\Blender\4.0\scripts\addons\sl_ct\operators.py", line 2303, in init_handler
    self._detector = Detector(context, event)
  File "C:\Users\silas\AppData\Roaming\Blender Foundation\Blender\4.0\scripts\addons\sl_ct\snapi\detector.py", line 75, in __init__
    self.start(context, event)
  File "C:\Users\silas\AppData\Roaming\Blender Foundation\Blender\4.0\scripts\addons\sl_ct\snapi\detector.py", line 88, in start
    engine.start(context, event)
  File "C:\Users\silas\AppData\Roaming\Blender Foundation\Blender\4.0\scripts\addons\sl_ct\snapi\raycast.py", line 179, in start
    self._add_collection_instance(empty, empty.matrix_world, empty.instance_collection)
  File "C:\Users\silas\AppData\Roaming\Blender Foundation\Blender\4.0\scripts\addons\sl_ct\snapi\raycast.py", line 95, in _add_collection_instance
    _space = space @ Matrix.Translation(-coll.instance_offset)
AttributeError: 'NoneType' object has no attribute 'instance_offset'

I'm using blender 4.0.2 and version 2.0.6 of cad transform on windows.