I made a first attempt at sulfide toning the other day. As a sulfide toner 'stop bath' I used a sodium sulfite solution (~1 tablespoon/litre). To my unpleasant surprise the stop bath reversed the print to the state before sulfide toning. This shouldn't happen should it?

My workflow:
- Adox MCC 110, neutral developer, acid stop bath, fresh fixer,
- 5 min water wash,
- selenium tone 1+19 for 2-3 minutes (noticeable discolouration),
- 30 min water wash,
- sulfide tone (Agfa Viradon New) 1+24 for 8 minutes,
- water wash ~1 minute,
- sodium sulfite solution wash for 5 min,
- final wash.

Could it be that Adox MCC simply does not respond to sulfide toner in the first place, and that the sulfide toning that I think I'm seeing (before applying the sodium sulfite stop bath) is just the colour of the sulfide toner absorbed into the paper? But then, no rinsing with water manages to remove this sulfide stain (or what it should be called), while the sodium sulfite stop bath does the (unwanted) trick in a couple of minutes.

What am I doing wrong?

Thanks for any help,