SCORM Dispatch LMS API Error

We utilize Storyline 360 to create 10-minute eLearning courses (not heavy with video). With those courses, we utilize Rustici's SCORM Dispatch tool to distribute our content to clients. 

Some of our clients experience the following error; however, the experience is inconsistent among end users. 

This site says...

An error has occurred:

Error - unable to acquire LMS API, content may not play properly and results may not be recorded. Please contact technical support.

Press "OK" to view debug information to send to technical support.

Notes on our current troubleshooting:

• There are known issues with IE and SCORM Dispatch. We have confirmed that end users are not utilizing IE.
• We have launched our SCORM Dispatch files on SCORM Cloud and do not experience this issue. 
• The courses are packaged with the latest Storyline update.
• Our SCORM Dispatch files must be uploaded as SCORM 1.2 files in an LMS. We have confirmed this is the setting. 
• There is no need to review the file itself, as this only happens with certain clients and within their environment, the behavior is inconsistent.
• We have provided whitelisting information for the servers that the dispatch file reaches out to when launching.

Can anyone help with some ideas?