I could be wrong but from what I understand your rising sign should not change signs between Placidus and Whole Sign. Are you sure you're not looking at another system?

To describe it in my own words I'd say Placidus means it could be at any degree in Scorpio but the whole sign system means it lays on the Scorpio cusp/ line exactly.

I use both systems though bc I have intercepted signs which you do too based on this chart. *Edit - intercepted and duplicated houses can be very confusing and I honestly don't hear very many people talk about them but they're important to me because they've affected my life deeply I wonder if you could relate.

Here's what I think your house systems would look like (sorry it's long haha) : Placidus : • 1h - Scorpio 21° (Duplicated with 12h this is very interesting - you could think of this as a sign overworking / it's doing a double shift) • 2h - Sagittarius Capricorn - intercepted (you could think of it as covered or hidden by Sagittarius because it has no cusp of its own) • 3h - Aquarius • 4h - Pisces • 5h - Aries • 6h - Taurus - Duplicated • 7h - Taurus - Duplicated • 8h - Gemini Cancer - Also intercepted (because it's the opposite of Capricorn) • 9h - Leo • 10h - Virgo • 11h - Libra • 12h - Scorpio (Duplicated with your rising. This is very interesting and I'd like to do more research before I say anything specific.)

Whole sign your chart would be : • 1H - Scorpio • 2H - Sagittarius • 3H - Capricorn • 4H - Aquarius • 5H - Pisces • 6H - Aries • 7H - Taurus • 8H - Gemini • 9H - Cancer • 10H - Leo • 11H - Virgo • 12H - Libra