Bug in UEL properties definition?

Hello,

I have a user-defined element which has been extensively tested and used "in anger". I recently added more properties to be used with this. I noticed that PROPS(13) consistently took the wrong value. As a workaround, I decided not to use this. However, upon adding more property definitions (up to 19), I find that PROPS(16) to PROPS(19) are susceptible to containing garbage (including zeros and NaNs).

Has anybody else come across this problem? If so, are there any solutions/workarounds?

Kind regards,
Ross.