Taking the liberty to copy and paste the response here from the Leica site:
"Further to my post (which was rather hurried) I don't think your M7 is "acting funny". If you use a DX coded film the viewfinder display will always show the speed detected. It will be steady if the ISO dial is set to DX and will flash if set to any other setting (it will also be steady if you set the film speed to the same rating as the DX code, i.e. 200 for 200). After 2 seconds the display will show the shutter speed if the shutter speed dial is set to "A" or the dot and arrows if set to a set speed. Look at page 81 of the instruction book which explains it fully. The only time the viewfinder display should show your set film speed is with a non DX coded film."
My M7 shows ISO 5000 when using non DX-coded Cinestill 800 cartridges.
"An ISO of 5000 in the range/viewfinder means the sensors are reading 5 conducting surfaces in the fim speed section. Keep in mind the 6th surface which is the 1 next to where the spool comes out of the cartridge always is conductive on both the film speed side & the film length/film latitude side....Your non DX coded cartridge may be somehow registering as the series: B,B,B,B,B,B which is the code for ISO 5,000...I've used it with both 100 and 160 DX coded film so far and both of these have registered fine. On the Rollei film there is black company contact information written in place of the barcode and black/silver DX contacts and the wrap is a light grey colour so i think you must be right that this is confusing the M7 and causing it to show 5000. "
It exposes correctly at the manually set ISO 800, it is just the cartridges unusual markings that cause this 'error'. Bottom line is the manual film speed setting over-rides everything. As it should.
