Created attachment 27720 [details]
Chart that causes problem (description follows)

Select the tab "Gantt", click to change the settings of the horizontal axis 
(NB this is the Y-axis). Change the sub-interval e.g. to 7.0. Close the file. 
Reopen it. See the Chart. Checking the sub-interval reveals it is set again to 
7.6 although the "automatic" button is not selected. 
You can select any other value, the sub-interval is always set to a value that 
creates a sub-set of the main-interval (e.g. 7.6, 3.8, 1.9)...
The sense is that the horizontal axis is time, main interval month 
(365/12=30.4), sub interval weeks (7) days.

HI, one for you.

You use a minor interval different from an integer factor of the major interval
to workaround the missing feature of real time axis. I must appologize that this
use was never intended though working somehow in older version. We plan to offer
real time axis with Issue 25706.
As workaround for the moment you can try to use the second y axis. For example
set the major interval of the main y axis to 7 and the major interval of the
second y axis to 30,4. Make sure that minimum and maximum are set to the the
same values in both y axis.

Apart from the missing time axis the scale tabpage needs to be fixed to not
allow settings which are restted afterwards.

reset to new