Installed the -proposed updates for both bamf and unity related packages.
Interestingly this not only fixes the brokenness in the Unity 5.12 -updates package, but it also fixes a slight cosmetic glitch from the Unity 5.10 (previous version in precise) package too: on that version, upon opening Gimp two icons would momentary show on the launcher, then one would disappear a moment later.
Fixed for me too.
Installed the -proposed updates for both bamf and unity related packages.
Interestingly this not only fixes the brokenness in the Unity 5.12 -updates package, but it also fixes a slight cosmetic glitch from the Unity 5.10 (previous version in precise) package too: on that version, upon opening Gimp two icons would momentary show on the launcher, then one would disappear a moment later.