It's not so much a issue that needs attention, just a link to instructions on how to enable NPAPI in Chrome as since version 42 of Chrome, it stops running .jnlp automatically and stopped the Launch button from.
Unfortunately but unsurprisingly it appears webstart is going the way of Flash, with Chrome now requiring a client-side option to enable the NPAPI plugin system, also rumoured to be removed entirely by end of year. Oracle advice being "Don't use Chrome" (!).
Posting how to enable NPAPI on the client doesn't seem appropriate given its impending death and that it isn't something you can expect a typical report consumer to feel comfortable doing.
But it's not dead quite yet. If Java is already on the client - often known to be the case - you can simply host a download link for the JNLP file, which the client would click the open the file to launch.
Long term, webstart reporting will need to transition to Mobile / web-based.