During the installation, the DBA would have been prompted to carry out the tasks below. If the colours aren't showing, please check the new $OA_HTML directory post upgrade? It may be this step needs to be redone.
2. Adding the Absence Calendar styles (DBA):
IMPORTANT: Do not interupt this patch session. Follow these
instructions in a different session.
1. As the APPLMGR user, login to the Application Tier (APPL_TOP) by
sourcing the environment file.
2. Edit the file Custom.xss or custom.xss, which is located in the
directory $OA_HTML/cabo/styles.
Note: the file will have either a capital 'C' or a lower 'c', depending
on the release.
3. Add the following line to the end of the existing import statements.
<import href="xxas_abscal.xss"/>
For example, if the file already has just one import for oa.xss,
the imports section would look like this:
..
<import href="oa.xss"/>
<import href="xxas_abscal.xss"/>
<styleSheet>
..
4. Remove the existing style sheet cache so that the imported styles
take effect:
rm $OA_HTML/cabo/styles/cache/*
5. If this system has multiple Application Tier file systems, repeat
steps 1-4 for each file system.
Without doing this, you won't see colours on the Absence Calendar - you'll just see a letter in each cell.