What Might Be Causing This Serialization Error? Craft Pro 3.0.7Notifications Plugin 1.0.6PHP 7.0

In trying to send notifications for new entries that have a checkbox field, we get this error in the logs:


  2018-05-14 09:19:32
  [192.168.10.1][1][-][error][UnexpectedValueException]
  UnexpectedValueException: Error at offset 0 of 2 bytes in
  /home/path/to/vendor/yiisoft/yii2-queue/src/serializers/PhpSerializer.php:32


This manifests as the notification getting stuck in queue, never releasing, always showing progress bar.

Removing only the checkbox field from this section, the notifications work as expected without any errors.

From what I read, serialization errors may result from encoding problems.

What else can I try to resolve this? Where else can I look?
Update the Notifications plugin.

From Craft Support:


  Ultimately Yii/Craft is using PHP's serialize() method to do the
  serialization, which has always had quirks with serializing different
  types of objects, especially the more complex those objects are.
  
  We try to only serialize simple objects and primitive data structures
  (arrays, strings, bools, etc.) to try and minimize those issues as
  much as possible.


From The Developer:


  Notifications are no longer queued as this causes a lot of issues with
  serialization. Will find a better solution for this in the future.


Prior to version 1.1.0, the Notifications plugin was attempted to serialize the entire entry to place it in queue.