You are using the FineOffset driver which has no concept of
rainRate so WeeWX should be calculating
rainRate from your rain data. Your statement:
> I think that this can be traced back to the update of 4.5.1 but I am not sure.
implies that rainRate was correctly calculated at some stage. Is this correct? If so do you know what WeeWX version you upgraded from or what version rainRate last worked under? There have been some changes to the WeeWX StdWXCalculate service recently (the StdWXCalculate service calculates derived observations such as rainRate) though from a quick look the current rainRate calculation code has been in place since v4.2.0. Looking at your wee_debug output everything appears to be correctly configured for rainRate to be calculated.
You say 'Rain Today show a positive value', which I assume means that rainfall data is being correctly recorded and displayed on the pages concerned? The FineOffset driver (fousb) does accept some debug settings that enable debugging of rain processing code in the driver, but on the basis of your rainfall data appearing to be correct there is probably not much point in turning this setting on and debugging the driver. There is not too much in the way of StdWXCalculate debug output in WeeWX, but its probably worth setting debug = 1. Probably also worthwhile running WeeWX directly to see what rain/rainRate data is being provided. Suggest you:
1. edit weewx.conf, set debug = 1, save weewx.conf
2. when it is raining stop WeeWX if it is running and then run
WeeWX directly. This will cause WeeWX to display loop packets (lines starting with LOOP:) and archive records (lines starting with REC:) on the console. Let WeeWX run for a few archive periods (we need to see 2-3 REC: lines) and take a screen capture of the output. Post the captured text back here.
3. take an extract of the WeeWX log from when you just started running WeeWX directly. Make sure you capture the full startup sequence as well as 2-3 archive periods. Post the log extract here, there should be nothing sensitive in the log extract but check anyway.
Gary