gimp-file-load not working in 3.2.4 on windows 10?

[Alb.gimp]

I just installed gimp 3.2.4 and am updating my old .scm scripts from 2.10.30.
I don't seem to be able to get the new gimp-file-load to work. I have tried all
variations I can think of. Below are two pertinent efforts.

Anybody have any good ideas for fixing it or is it a bug in gimp?

try 1

                  (define fn "E:\sys_add\gimp_scripts\batch_in\BNP627O.tif")
 (display (string-append "fn: " fn "\n")) 
                  (define fn_len (string-length fn))
 (display (string-append "fn_len " (number->string fn_len) "\n"))     
                  (define image (car (gimp-file-load RUN-NONINTERACTIVE fn))))  
gives:
GIMP-Error: Calling error for procedure 'gimp-file-load':
Procedure 'file-tiff-load' has been called with value '<not transformable to string>' for argument 'file' (#2, type GFile). This value is out of range.

try 2

                  (define fn "E:\sys_add\gimp_scripts\batch_in\BNP627O.tif")
 (display (string-append "fn: " fn "\n")) 
 (display (string-append "string? fn: " (if (string? fn) "true" "false") "\n")) 
                  (define image (car (file-tiff-load RUN-NONINTERACTIVE fn))) 
gives:
fn: Eys_addgimp_scriptsbatch_inBNP627O.tif
string? fn: true
batch command experienced an execution error:
Error: Invalid value for argument 1