fileBinary thumbnail in Node, passed to Browser, cannot display in any format.

The Scenario: We have a Nodejs app that uses the dropbox javascript SDK. On the front end, we have Web and iOS clients that talk to our Node app and ask it for file listings. That much works. We get our results. 

The problem: Thumbnails. 

In node, I get a fileBinary by calling:

filesGetThumbnail ({path: <mypath>, size: {'.tag': 'w64h64'}}))

I serve this thumbnail to our front end, per recommendations: 

Buffer.from(fileBinary).toString('base64')

I've also tried many other variations, such as 

Buffer.from(fileBinary, 'binary').toString ('base64') 
// as well as 'utf8', 'latin1', new Buffer() instead, etc 

I've verified that our client receives the thumbnail just as Node sends it. So far so good. 

But I cannot get the image to display.

I've tried a dozen variations in our React client, such as: 

<img src={"data&colon;image/jpeg;base64," +imageData} />

<img src={"data&colon;image/jpeg;charset=binary;base64," +imageData} />
// also more charsets, a space, atob(), several stackoverflow solutions,...

But 100% of all combinations of encodings and charsets result in broken images. 

I've noticed that there are essentially 2 types encoded formats I can produce and send to the browser: 

#1 looks like "/9j/4AAQSkZJRgABAQAAAQABAAD/2wCEAAYEBQYFB etc.

#2 looks like "77+977+977+977+9ABBKRklGAAEBAAABAAEAAO+" etc

Looking online, This decoder prefers the second format, while this encoder produces the first format. 

But either way, in either format, none of these display, all appear broken.

Can someone please advise? 

Thanks,

Lucas