PROBLEM SUMMARY:
If Email Content is mapped to Text Area (Rich) field on Incident (without keyword), and Incidents are created through Email and, then changes applied to Incident fields through workflow/process builder/flow are overwritten with initial values of the fields.

DESCRIPTION:
Issue observed when,

1. Incident is created through Email AND
2. In Remedyforce Administration > Configure Email > Incident – Email Settings, Email content is mapped to Text Area (Rich) field and keyword for mapping is kept blank AND

3. Workflow/Process Builder/Flow is used to update incident fields, while creation of incidents through Email.

Workaround 1:
If you want your customizations (For e.g. Field Updates using Workflow/Process Builder/Flows etc.) around Incident creation through Email to work, modify mapping under Remedyforce Administration > Configure Email > Incident – Email Settings.

1>Specify Keyword for all mappings with Text Area (Rich) field.
2>Map Email content to Text Area (Long) field (without keyword).
3>Create field update action in Workflow to map content of Text Area (Long) field with Text Area (Rich) field.
 
When Incident is created through Email, Email body content will be mapped with Text Area (Long) field and using workflow field update action, same content will be updated in Text Area (Rich) field in plain text format. And embedded images will be saved to Files or Notes & Attachments section of Incident.
Note: Formatting will be lost. However, you won’t need to modify any of your other customizations.

Workaround 2:
You need to modify all the Processes/workflows/flows, where entry criteria of Processes/workflows/flows are satisfied while creating incident through Email.

For Process Builder:
If you are using process builder to update incident fields (for incidents created through Email), modify your process to have time-based actions and with conditions as below.

(i) Scheduled Actions can be added in process if Start the process* = only when a record is created is set for your process. OR option “Do you want to execute the actions only when specified changes are made to the record?” is selected under Process Criteria.
(ii) Under SCHEDULED ACTIONS, click Set Schedule to add details as below and Save.           
(iii) Click + Add Action under SCHEDULED ACTIONS and define appropriate action.

For Workflow:
If you are using workflow to update incident fields (for incidents created through Email), modify your workflow, to have Time-Dependent Workflow Action.

(i) Go to Setup > Workflow Rules > Open your Workflow.
(ii) Add time-dependent workflow actions. [To add time dependent actions, you need to temporarily deactivate workflow.]
Note: You can add time-dependent workflow actions only if Evaluation Criteria for your workflow is set to
1>created
2>created, and any time it's edited to subsequently meet criteria

 
For Flow:
If you are using flow to update incident fields (for incidents created through Email), create an intermediate process builder with time based scheduled action to call your flow. In this case, you may need to modify entry criteria for your flow.

Only active, Autolaunched Flows are available to be called from Process Builder.

Follow similar steps as mentioned in workaround for Process Builder