Hi,
Strange that it only occurs 50% of the time.
Try the following to see if it resolves the problem or at least narrows down the cause of the problem further.
Being intermittent you may have to leave it for a while after doing each of these procedures until you know one way or the other whether it still happens.
[https://www.hardreset.info/devices/motorola/motorola-moto-g5-plus/wipe-cache/|Wipe the cache partition] and then check if the problem still occurs.
If still occurring, start the phone in [https://support.motorola.com/us/en/solution/ms116299|safe mode] and check if the problem still occurs.
if it doesn’t happen when in safe mode, then a ''downloaded app'' is the cause of the problem. You will have to uninstall each ''downloaded app'', one at a time and check the phone in normal mode between each uninstall, to see if the problem is still there or not. When the problem no longer exists then the last ''downloaded app'' that was uninstalled is the culprit. A ''downloaded app'' is one that you downloaded and installed and wasn’t pre-installed on the phone when you first got it.