We are frequently getting the following exceptions in prod logs:
Exception Description: cannot be null or blank. page: Declare_pyDisplay.pyDisplay. Details: Invalid value for aReference passed to com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.getProperty(String, char)
It looks to be the same issue reported by @M.PRASAD over here. Customer support engineer provided this support article before the closure the SR. You can try the suggestion provided in the support article and confirm the resolution as the resolution was not confirmed by Prasad in SR or Community post.