I am using the startprocesswriter function in a bind and I can not get it to wor

I am using the startprocesswriter function in a bind and I can not get it to work with Appian 7.6 or 7.7. It is always making it to the List of Variant portion of code in the plugin. Below is my sail code trying to use the plugin.
load(
local!testBool: bind(get: ri!testBool, set: fn!startprocesswrite(processModelId: 54, processParameters: {{param1:"yes"}})),
a!sectionLayout(
label: "Lorem Ipsum",
firstColumnContents: {
a!buttonLayout(
primaryButtons: {
a!buttonWidget(
label: "Start Process",
value: true,
saveInto: local!testBool
)
}
)
},
secondColumnContents: {
/* Add components here for a two-column section */
}
)
)

This calls a very simple start and end node only process with one parameter called param1. Looking at the code I was thinking this should work fine, but it does not and the expression is returning null. I get the following er...

OriginalPostID-135572

OriginalPostID-135572