Please ask specific Artlantis questions such as this on the Artlantis forums. Artlantis is made by Abvent and has its own enthusiastic user base there:
http://www.artlantis.com/_forums/index.php
With 4.1, if the sun is entering the room, you can get reasonable results without neon glass by adusting your radiosity settings.
But in any case, what you are experiencing suggests that you either do not have the neon power high enough (default is fine though), or you do not have the neon enabled for your view. See the attached screenshot: you must check the box shown to enable the neon shader to generate illumination in each view. Still, it can generate strange artifacts at times.
One of the forum moderators
AC 28 USA and earlier • macOS Sequoia 15.2, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB