Hello,
APEX version: 4.2.5.00.08
I was able to reproduce this issue on apex.oracle.com.
The theme I use is Theme 25 - Blue Responsive. I experienced the same problem in other (custom) themes as well.
Here's what I did. I created one parent region and two sub regions. The two sub regions are assigned "Form Region" as template. The parent region is assigned a custom template. This is how the definition of the custom template looks like:
Definition > Template
<div>
#TITLE#<br>
#SUB_REGIONS#
</div>
Sub Regions > Template
<div>
#SUB_REGION#
</div>
Both sub regions are identical, which means that there is no difference between the settings of the region items. You would expect that the sub regions look exactly the same... But that's not the case since the grid layout is only applied to the items in the first sub region. Subsequent sub region items completely ignore the specified grid layout settings. This behaviour only occurs when the parent region template includes a definition for sub regions. The sub region items are rendered normally when removing the sub region definition from the parent region template.
Here's an example on apex.oracle.com: https://apex.oracle.com/pls/apex/f?p=29319:1
Is this a known bug or am I doing something wrong here?
Thanks in advance,
Nick