1. I have generated "new" as a rec709 gray scale using the virtual probe and updated Target Luma by clicking Auto. Then I have saved it.
2. Then I have opened it again (Target Luma is correct), un-clicked Auto and closed it.
3. Now when I open it again, I find in Target Luma the arbitrary value stored in config.ini (see screenshot)

That is correct, with Auto disabled.
If you want the Profile metadata to update the Min/Max, Auto has to be enabled.
With Auto disabled the 'saved' manually set Min/Max values are used, or those from the selected target colour space, depending on what was set/selected last.
It provides full flexibility, and the operation is explained in the user guides.

Steve

Operation is clear, but that is about to what you measure.
I mean, if I measure, and I want the the profile evaluate to which ever Target Luma, then I update it and I save the profile
The expectation is that when I reopen the profile I find the same value I have saved.

Take in account this paradox:
1. I am doing an power gamma calibration with 120 Nits as target, It comes with a max of 110 Nits. I close it.
2. Now I am doing another one at with 200 as target. I close it.
3. Some time later I open the profile generated at 1. I find a target of 200 Nits .... Where is its original target? Basically CS has lost one of your profile data!
Obviously you can dump the metadata and write them manually, as that data is only hidden

No - You enable 'Auto', as stated above, before you open the profile.
That will use the Min/Max from the profile.

However, if you want to open a number of profiles, and compare them all to a set target Min/Max - sat the SDR standard of 100 nits for peak white - you do that by not enabling Auto before opening the profiles.
You have the ability to choose what target data to use.

Total flexibility, which is always the aim of ColourSpace.

Steve

Have a look at the attached profile: I have set Max luma = 120. The profile has 110 max. When you do "Manage => Displaying" you loose the Max Luma information I have set at measurement time. On the opposite, that profile in the report shows correctly: I can see what I have set at measurement time and I can eventually change it.


The way I wish it should work, you can achieve that by displaying all the interested profiles and setting Target Luma=100 on them.

P.S:
I have fallen on that despite I usually click auto: I have done a DV calibration (so Max Luma was 7xx Nits) and then a verification (absolute gamut set auto to 0). So, displaying old SDR profiles I was very confused and I have started investigating. Only now I have an understanding of what happened.

If you insist with your "Total Flexibility", you should address that in the manual: the need of eventually set Target Luma and Auto in a profile before displaying profiles is not trivial at all!

Attached file: test.bcs

From the User Manual:
(The Target Min/Max values are also auto-updated from a re-opened profile, and from any Black/White patch measurements made, if the ^ up-arrow Auto option is set as the default in Profile Luma options.)

I have tested with your 'Test.bcs' profile, and all works exactly as expected/explained.
But, I have no idea what "Manage => Displaying" is?
And yes, you can also "...achieve that by displaying all the interested profiles and setting Target Luma=100 on them."
All works.

Steve

Ok, manual explains. I have missed that, even if I had read that section. Sorry.
My test.bcs was saved with a Target Max Luma of 120 Nits (you can see that in the Metadata). My concern is that at re-opening time (I do that from "manage", selecting that profile and clicking on the Display button) that values is overwritten in profile in all the cases (i.e, I have to remind that, or check in metadata, or use report, to retrieve its saved value). Correct, or I am missing something? Off course a yes does not imply that is also your concern.

The auto update works. That my preferred choice. A pity that the selection of an absolute target profile reset it and confused me.

Ah!
I now understand the issue you are trying to explain!
The Target Min/Max Luma is NEVER restored from a profile.
It never has been, and has never intended to be...
Only the Profile Min/Max Luma is ever restored, with the use of 'Auto' as described.

Nowhere in the User Manual/Guides is there any mention of Target Min/Max, other than operating as stated.

Steve

The next release will have a change with the Target Min/Max loaded from a profile, if the profile was saved without the 'Auto Min/Max' update option enabled.

Steve