In addition to SOLO not currently allowing stack requests for books from the VHL stack, we've also discovered that stack requests are not always working to request books from the Bodleian stacks to the VHL. The problem here is that the VHL is not listed as one of the possible pick-up locations, and unfortunately this means that we can't override this for you from the staff side. I have reported this and we hope it'll be fixed soon, but in the meantime I'm afraid you will need to go to another library or reading room to consult Bodleian material.
This problem doesn't seem to be affecting oversize books, which continue to only be available to be requested to the VHL.
There is also a separate problem where some readers are not able to place any stack requests at all, despite always having been able to do so. This is also being investigated, and the good news is that staff can override this block so please ask us to place stack requests for you if you find you are not currently able to do so yourself.
If you do come across this, or any other problems with stack requests to the VHL, please do let me know.