Shiny App appears not to be reading server.R

I have an app that runs fine locally; however, when I upload it to my personal server, none of the components rendered in the output of server.R are rendering. Even things as simple as output$test <- renderText({return("Test")}) are showing as blank. The ui.R still reserves a place for these, and their divs are visible when I inspect the page.

Further, I added messages to the server.R file, and none of them are logged (including message("Server on") at the very top of the function).

I added options(shiny.trace = TRUE) to the top of global.R. When run locally, I get a number of SEND messages. However, when run on the remote server, the only messages logged appear to be RECV, e.g.:

SEND {"config":{"workerId":"","sessionId":"fe3f9f7f1fad0fbfe02847d7f19f9121","user":null}}
RECV {"method":"update","data":{"user":"fake"}}
SEND {"errors":[],"values":[],"inputMessages":[]}
RECV {"method":"update","data":{"password:shiny.password":"password"}}
RECV {"method":"update","data":{"login:shiny.action":1}}

The rest of the Shiny apps on this server appear to still be working, so I am at a loss. This previous discussion appears to have had a similar problem: "output" served by Shiny Server does not display on laptop However, there was no resolution. I tested this from my laptop (Chrome and Firefox) and phone (Chrome), and get the same result on both.

I believe that I tracked down the problem. My ui.R included some javascript (to find the screen size for some scaling, like what is described here). However, I had changed all of the Shiny.onInputChange to Shiny.setInputValue (which is the officially documented method). However, the version of shiny on my server was apparently quite old (1.0.3), which predated the addition of Shiny.onInputChange. When I update shiny on the server, everything worked as expected.

It is still not clear to me why this error caused the complete failure of the app, particularly without any message in the log.

Have you checked for errors in the browser console? Very often Shiny "fails quietly" when the problem is on the javascript code.

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