Calculation Manager Rules that are still on Planning don't show up on Calculation Manager

In my 11.1.2.3.500 setup, I recently faced an issue with Calculation Manager Rules that were present on Planning forms inside the Planning Application, but however, on expanding the Calculation Manager->Planning App->Plan Type->Rules, it did not display the rules inside. These rules were imported manually earlier and suddenly disappeared. I could not really find what caused it but here are the steps to recover the BR's from planning tables to calculation manager:

1. Access the appropriate Planning application repository and its table HSP_CALC_MGR_RULES

2. Create a new text file with following content

3. Copy the contents in the Body column of the HSP_CALC_MGR_RULES table and paste its contents between the tag in the file created in step 2.
4. Save file as XML file
5. Within the Calculation Manager navigate to “File” -> “Import…” to import the Business Rule into Calculation Manager .

Using this I could restore all the rules back.