It may feel as an old question, but i see some strange thing.
Regarding the stock type change during WT confirmation.
Respective configuration is done such Mandatory, different Av grp.
When i run the scenario, i see the documents such IBD, WT are being posted successfully and i also see the posting changes are triggered in ERP and the stock is showing in correct SLOC in ERP as i expected.
But still the stock type is F1 in WT which is suppose to be F2.