Strange problem with Audacity's Graphic Equalizer

For some reason, since yesterday, the sliders in the Audacity EQ are not working correctly. I work a LOT with sound samples, and am used to slightly modifying samples with the EQ, for example, removing disturbing hissing sounds at about 5kh. But suddenly, when I move the 5KH slider, it does not affect the sound; yet moving the 12KH slider DOES affect the 5KH frequency. The same for all the other sliders; sounds in the 400h range are no longer affected by moving the 400h slider, instead, I must now move the 2kh slider to affect the 400h range. I thought by updating the program (from 3.4 to 3.7) the problem might get fixed, but this is not the case. What could possibly be causing such a problem? Thanks in advance for any tips you may have…

TDR Nova compressor/equalizer plugin (free) works with Audacity 2 & 3.
It has a realtime graphic display of the effect of equalization settings.