Not sure if this is still an issue, but in about 2017, there was an issue with lowercase bins not reporting on Stock Status.
Here is a calculated field you can add to a BAQ to check for these.
There are also posts on writing BPM for preventing lowercase letters during bin creation.
Epicor does have a SQL fix for renaming bins to uppercase you can request though support.
CASE
WHEN LOWER(PartBin.BinNum) COLLATE Latin1_General_CS_AS <> PartBin.BinNum
THEN 1 ELSE 0
END
Alternative Code (searches entire string)
CASE
WHEN PartBin.BinNum LIKE ‘%[a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z]%’ COLLATE Latin1_General_CS_AS
THEN 1 ELSE 0
END