Magnets and alignment

Hey folks,

I am a bit helpless right now and my google fu didn’t bring back any solutions:

I have a new Mac, installed Omnigraffle and copied over my .graffle diagrams (see details below).
My problem:
When I want to add a magnet to a shape it does not show me the alignment lines (Smart guides?), e.g. the mid of a side of a shape. See here in the manual, I refer to the blue lines.

So I have to put in the magnets free-hand which - of course - is a mess (I can somewhat mitigate by using the predefined magnets under edit but it isn’t the same).

I tested it with my existing documents I carried over from the old installation and a new, blank document.
Screenshot: No guiding lines

Smart stuff enabled: Arrange -> Guides -> Smart *

Is there a setting I didn’t enable or what could have changed?
Thanks a lot folks!

*** Update: ***
On a hunch I installed 7.5 on my new system and it works.
What did change in 7.6 that breaks this?

New MAC:
OmniGraffle build details:
Product: OmniGraffle-7.6.x
Tag: OmniGraffle/7.6.1/GM-v185.4
License: PRO
Mac OS: 10.13.3 (17D47)

Old MAC:
OmniGraffle build details:
Product: OmniGraffle-7.5.x
Tag: OmniGraffle/7.5/GM-v181.4
License: PRO
Mac OS: 10.11.6

Guides for magnets did indeed go missing between OmniGraffle 7.5 and 7.6. They’re back in 7.7 though!

OmniGraffle 7.7 isn’t out quite yet but you can get a pubic test copy here:

Man, I was going stir crazy over this.
So I’ll just cling on to my 7.5 installation and will try out 7.7 once it is GA.

Thanks a lot for sharing the information and the dev goal!