gl_cmap shader compilation failed

Hi Sylvain, Since I switched to Ubuntu 20.04, I am not able to get Posphor working with osmocom_fft. I am getting the following error: [!] gl_cmap shader compilation failed (cmap_simple.glsl) [w] Color map shader 'simple' failed to load, will use fallback [!] gl_cmap shader compilation failed (cmap_bicubic.glsl) [w] Color map shader 'bicubic' failed to load, will use fallback [!] gl_cmap shader compilation failed (cmap_fallback.glsl) [!] Color map shader 'fallback' failed, aborting gr::log :ERROR: qt_sink_c0 - Failed to initialize fosphor The app is running, but the render area of the spectrum is completely blank. I am on your "gr3.8" branch. OpenCL is exactly the same as on Ubuntu 18.04 (I need the older 340 Nvidia driver on my old NVS 4200M, if you remember), GLFW is the latest master. Everything compiles just fine, only at runtime this issue presents itself. If you have any idea, that would be lovely. Regards, Csaba