Q: Is it usual for the status to remain "Editor invited" for 5 months?

If the status changed from "With Editor" to "Editor invited," it means that the invitation for an Associate Editor (AE) for your paper has been sent out, but the editor has not yet accepted the invitation. Thus, your paper has not really made any progress since submission. It should ideally not take 5 months to assign an AE. Please send an inquiry to the journal immediately and make sure you follow up every 2-3 weeks. If you don't see a change in status in another month, it would be advisable to withdraw your paper and submit it to another journal without wasting any more time. 

Related reading:

• Why does the status change from "Editor Assigned" to "Editor Invited" and back to "Editor Assigned"?
• Why has the status date changed while the status remains unchanged at "Editor Assigned"?