Can No Longer Set Up Guest Account in Nighthawk App

Starting approximately two weeks ago, I have been unable to set up or alter guest wifi accounts through the Nighthawk app. I can still control them through routerlogin.net, so I do not believe it is my router at fault. I do prefer to use the app as a time limit can be set, and I don't have to remember to turn guest accounts off when finished.

I have uninstalled and re installed the app, have done this on both devices I have used with the app; I have even done a factory reset on my router, but the app will no longer allow me to control guest accounts. I open Guest Account, change the settings, click Save, but it will not complete the changes.

It is an ax15 router, which is up to date, and iPad 6's, which are both up to date; the app is also up to date.

Thank you, Ms. Renoir