REW version is 5.20.13You don't mention which releases you are referring to, but there haven't been any new settings affecting EQ filter generation in a long time. Probably easiest if you post an example measurement (i.e. the mdat file, saved after you generate the EQ filters) along with a screen shot of the settings you are using in the Filter Tasks pane.
That did the trick. I suspected it was simply a setting I had messed up. Much appreciated!You have set the flatness target to 6 dB, which tells REW to stop trying to apply EQ if the response is within 6 dB of the target. If you set that to the usual 1 dB figure the behaviour should be as expected.