Setting a loaded raster to read/write in VBA (Microstation v8.5)

I'm trying to change the Read/Write status of an attached raster through VBA.

Recording a macro gave me the following code.

SetCExpressionValue "tRMDlgSettings.bOpenReadOnly", 1, "RASTMGR"

This worked to change it back and forth if I used a 1 or 0, but after testing a few times it no longer applies the change.

If I have the attachment settings window open, it will uncheck the box but the apply button is greyed out still. If I click okay after VBA unchecks the box, nothing happens. If I click it myself I can then click apply or ok and it works fine. Any ideas?

I tried to replicate results in Powerdraft but the attachment settings dialog doesn't seem to exist.