Door Sensor NOT Triggering Alarm

HiHad the Ring alarm set up for several months without an issue until this last week or so. I have a sensor placed on the front door of the house which leads into a porch prior. I have now put the keypad in the porch so you can enter the house, trigger the sensor and then have 30 seconds delay to turn the alarm off. However, when I open the front door. The sensor doesn’t trigger the alarm and start the 30 second countdown. The only way I can trigger the alarm is to open the inner porch door and then the motion sensor I have in the entrance detects the movement and then it works. I’ve looked in the settings of the front door sensor and it’s registers when the door is open and closed correctly. So I can’t understand why it isn’t working when the alarm is armed and I return home. Any ideas?