When you open Viewflow it goes into an infinite spinner which never resolves.
This issue occurs when an Activity name contains an apostrophe ( ' ).
The process instance xml contains the Html Encoded character apostrophe (';) for a specified activity name and for same activity name the apostrophe ( ' ) is used defining the line start and end activities. This will cause the drawing of the activities to fail on the canvas because the activity will not be possible to find.
The fix for this issue has been included in K2 FIVE RTM Fix Pack 13. Please log a ticket with K2 Support referencing this KB article to request the fix.
Please follow this Workaround if you don't want to apply the Fix Pack at this time:
1. Find the process that still contain (') by editing the .kprx in Notepad and doing a search for (') and then deploy the workflow.
2. If you know which activity contains the apostrophe ('), remove the one and re-add the activity again.