Here is a list of things to check :
Did you clean the wide-angle lens and your smartphone’s lens ? Is the wide-angle lens correctly aligned on your smartphone’s lens ? You should see the smartphone’s lens properly centered inside the wide-angle lens, when looking through the wide angle lens. Did you check that the nodal point of your lens is still correctly aligned with the rotation axis of the tripod ?
Avoid blurry pictures
Older smartphones (before 2016) might have difficulties focusing correctly in some situations : very close objects (less than 1m) on distant background, very dark areas, or undifferentiated white walls.
When shooting, did you check that all images are correctly focused, and appear crisp (not blurry). If necessary, tap on the screen to force the focus on a particular object or wall. You can always review the last picture (click on the thumbnail at the bottom of the screen). This will allow you check (pinch in and out !), and choose to continue or discard the last picture and reshoot it.
Avoid parallax errors
Even though Nodalview has been designed from the ground up to avoid them, parallax errors (broken lines or distorted geometry in your pano) may appear in rare circumstances, more likely with close objects (less than 1 meter away). First of all : check that you smartphone is correctly mounted on the tripod. Make sure that the lens is aligned with the rotation axis of the main pole. Make sure that the tripod did not move during the capture of the panorama.
If the problem persists, try the following : Shoot the close object or the area exhibiting parallax errors first, so that they appear on the center of a single image. Alternatively, try turning your tripod 20 degrees right or left from your initial position, or move your tripod in another place in the room. As a rule of thumb you should always point the camera towards the closest object to the lens and make sure it is fully framed in the first picture.