Really Challenging: Unable to click elements in a series

In a mobile app, I am trying to access three elements on a page. using my script I am able to access the three elements individually but when access in series the script fails after accessing the first element whatever the order I follow.

Three elements are:

  1. start time: a popup to select the start time
  2. end time: a popup to select the end time
  3. a drop-down to select an option

if I enter start time first, I cannot enter end time and select the drop-down
if I enter end time first, I cannot enter the start time and select the drop-down
if I select the drop down first, I cannot enter start and end time.

in any of the above cases, it says the element is not visible with the provide id/XPath.

details:
I am using Appium 1.13.0 with python 2.7.15 with Android Emulator Nexus 5x

Logcat:

07-30 18:38:03.582 9628 9640 E QueryController: Got null root node from accessibility - Retrying…
07-30 18:38:03.836 9628 9640 E QueryController: Got null root node from accessibility - Retrying…
07-30 18:38:04.091 9628 9640 E QueryController: Got null root node from accessibility - Retrying…
07-30 18:38:04.344 9628 9640 E QueryController: Cannot proceed when root node is null. Aborted search
07-30 18:38:04.345 9628 9640 E QueryController: Got null root node from accessibility - Retrying…
07-30 18:38:04.598 9628 9640 E QueryController: Got null root node from accessibility - Retrying…
07-30 18:38:04.851 9628 9640 E QueryController: Got null root node from accessibility - Retrying…
07-30 18:38:05.103 9628 9640 E QueryController: Cannot proceed when root node is null. Aborted search
07-30 18:38:05.104 9628 9640 E QueryController: Got null root node from accessibility - Retrying…
07-30 18:38:05.358 9628 9640 E QueryController: Got null root node from accessibility - Retrying…
07-30 18:38:05.610 9628 9640 E QueryController: Got null root node from accessibility - Retrying…
07-30 18:38:05.862 9628 9640 E QueryController: Cannot proceed when root node is null. Aborted search
07-30 18:38:05.862 9628 9640 E QueryController: Got null root node from accessibility - Retrying…
07-30 18:38:06.115 9628 9640 E QueryController: Got null root node from accessibility - Retrying…
07-30 18:38:06.368 9628 9640 E QueryController: Got null root node from accessibility - Retrying…