Unable to have planner update a sharepoint list

[Nelsom20]

I have a pair of flows that I want to work in parallel with each other, the first takes items from a SharePoint list being used as an issue tracker, and pushes them to planner and thus MS Teams. This one seems to be working correctly. 

The second one that takes task competition back to the SharePoint list doesn't work. The issue seems to be that sharepoint and planner use different ID systems and there is no easy way to tell planner or the flow what the sharepoint ID of a task is. 

This task from SharePoint the ID is "14", in the create planner task flow there isnt a field or anything I can have this dynamically placed into outside the title of the of the task. I have tried to make it so that the title is  "<Titleonsharepoint>:TaskID:<sharepointtaskid>"  but when trying to use the split function I get an error saying the expression is not valid. 

Example   the title would be      Test Issue 4:TaskID:15    (I also tried just using a colon as a delimiter, same effect) 

example expression:          split(triggerOutputs()?['body/title'],":TaskID:")     <- Returns "The expression is invalid"

Tried various grouping of parenthesis and array operations to take just the second element but nothing seems to work outside hard coding in the ID I know sharepoint is expecting, which works once but of course never again. 

Anyone have a solution to this or a way to accomplish it?