WHMCS WP Integration Hummingbird Conflct

Hello,

WHMCS Wordpress Integration plugin is producing an error after installing Hummingbird and enabling GZIP compression and browser caching as follows:
-------------------------------------------------------------------------------------------------------------------
ERROR MESSAGE
-------------------------------------------------------------------------------------------------------------------
Warning: file_get_contents(/home/dir2376/public_html/wp-content/plugins/whmcs-wordpress-integration/cache/ae7d9afce088b31b1f31c469bb689146.txt): failed to open stream: No such file or directory in /home/dir2376/public_html/wp-content/plugins/whmcs-wordpress-integration/includes/class-whmcs-wordpress-integration.php on line 376
-------------------------------------------------------------------------------------------------------------------
This is not due to a plugin conflict as the configuration worked prior to installing Humingbird.

The problem is that the error persists after deactivating Humingbird. It looks as if the caching is not disengaging based on the fact that the error message suggests a missing cache file: /whmcs-wordpress-integration/cache/ae7d9afce088b31b1f31c469bb689146.txt
I tried re-installing the the WHMCS Wordpress Integration plugin several times to see if refreshing the files would eliminate the error since the error is due to a call on line 376 of the following file: /includes/class-whmcs-wordpress-integration.php

It seems the missing caching file here: /plugins/whmcs-wordpress-integration/cache/ae7d9afce088b31b1f31c469bb689146.tx (I checked and it not in the directory) is due to a lingering affect from Hummingbird but I'm not completely sure as I do know if the WHMCS Wordpress Integration plugin generates its own caching files.

Can someone please take a closer look at this and assist with restoring the normal functionality of WHMCS Wordpress Integration?

Thanks,
Mike