Hi, welcome!
It's hard to help you with out seen any code, so please try to turn this into a reproducible example of the problematic code inside your shiny app. You can follow this guide to do it.
Shiny issues can be challenging to resolve relative to other problems with your code or statistical methods. Shiny apps are often large, complex projects with interacting files.
When seeking help from others it is considered polite to:
First, do your best to work through RStudio's debugging tools to diagnose your issue on your own. Often those shiny logs and tracebacks are useful to others trying to help out.
Second, strive to minimize the effort required to replicate your issue. You can do this with a reproducible example ("reprex").
Shiny Debugging
Errors in Shiny code can be difficult to track down. If you don't know where your problem is coming from, you can track it down with some o…