I'm on a MacOS and using Catalina. I've been experiencing this problem for some time and the only fix is to restart LR. When I'm using the adjustment brush in LR it will turn into a pointer on part of the screen and LR will not respond. This problem seems to happen when I've been using LR for a while. The brush turns into a pointer on a different part of the screen every time this happens.
Please post your System Information as Lightroom Classic (LrC) reports it. In LrC click on Help, then System Info, then Copy. Past that information into a reply. Please present all information from first line down to and including Plug-in Info. Info after Plug-in info can be cut as that is just so much dead space to us non-Techs.
Lightroom Classic version: 9.4 [ 202008061458-dbb2971e ] License: Creative Cloud Language setting: en-US Operating system: Mac OS 10 Version: 10.15.6 [19G2021] Application architecture: x64 Logical processor count: 4 Processor speed: 3.4 GHz SqLite Version: 3.30.1 Built-in memory: 8,192.0 MB Real memory available to Lightroom: 8,192.0 MB Real memory used by Lightroom: 1,779.0 MB (21.7%) Virtual memory used by Lightroom: 10,539.7 MB Memory cache size: 473.8MB Internal Camera Raw version: 12.4 [ 555 ] Maximum thread count used by Camera Raw: 3 Camera Raw SIMD optimization: SSE2,AVX,AVX2 Camera Raw virtual memory: 394MB / 4095MB (9%) Camera Raw real memory: 404MB / 8192MB (4%) Displays: 1) 5120x2880
Graphics Processor Info: Metal: AMD Radeon Pro 570