Functions taking userdata and registered via bind() never complete in the JS script?

[g40]

Another question re binding (slightly different to #922)

TL;DR. C++ functions registered via bind() with userdata can be called from Javascript, but the promise they return never completes.

Any thoughts? MTIA.

Much more detail:

2 different C++ functions are registered using bind().

// C++
// 1st variety
// sync appears to work in both directions, so JS -> C++ -> JS
std::string callout1(const std::string& arg)
{
	std::string ret = std::string("{ \"status\": true }");
	std::printf("%s => %s\n", arg.c_str(), ret.c_str());
	// JSON status message
	return ret;
}

// 3rd variety
std::string callout3(const std::string& arg, const std::string& arg2, void* data)
{
	webview::webview* pwv = reinterpret_cast<webview::webview*>(data);
	std::string ret = std::string("{ \"status\": true }");
	std::printf("%s %s (%p) => %s\n", arg.c_str(), arg2.c_str(), pwv, ret.c_str());
	// JSON status message
	return ret;
}

// both get invoked, but the 2nd form never completes in the .JS script
w.bind("callout1", callout1);
w.bind("callout3", callout3, userdata);

Log detail from the console (Edge on Windows 10 21H2). The line annoted with *** => shows success

callit called  callout1 ƒ () {
        var seq = RPC.nextSeq++;
        var promise = new Promise(function(resolve, reject) {
          RPC[seq] = {
            resolve: resolve,
            reject: reject,
          };
ret =>  Promise {<pending>}

*** => index.html:36 success:  {status: true}

callit  called  callout3 ƒ () {
        var seq = RPC.nextSeq++;
        var promise = new Promise(function(resolve, reject) {
          RPC[seq] = {
            resolve: resolve,
            reject: reject,
          };
ret =>  Promise {<pending>}