Revitalize Rune shows negative healing bonus for HP cost champions!

Played a game of ARAM with Zac using the Revitalize Rune to increase my own healing received from my passive blobs. However, this was offset by my HP costs, as shown below:

https://i.imgur.com/cxO36Aq.png[/img]

^First we start at -3 healing bonus. Then...

https://i.imgur.com/DrwVjBX.png[/img]

^After casting Q, we're now at -9 healing bonus. Then...

https://i.imgur.com/udPoqIO.png[/img]

^@ -10 healing bonus after casting W. Then...

https://i.imgur.com/tcgIMuv.png[/img]

^@ -14 healing bonus after casting Q again.

Now here's the REAL kicker...

https://i.imgur.com/SZvpsa8.png[/img]

^We now have -1847 healing bonus!!! How? This happened after my passive blobs were proc'd! I didn't die before my blobs reformed, but I died shortly afterwards.

This really needs to be looked into Riot.