@AnugrahR_George 

could be because of version mismatch between Workflow studio plugin and Flow Designer plugin

check this KB which talks about this

Unable to Open Flows in Workflow Studio -> repair Workflow Studio Plugin which updates Flow Designer Plugin and then logout and login again

💡 If my response helped, please mark it as correct ✅ and close the thread 🔒— this helps future readers find the solution faster! 🙏