Need non-negative Q-word to specify tool number with M61/Clears with G0?

When I use NCAM and toggle the "delete block" button I have been getting an error I was unable to clear without exiting linuxcnc.  I did see it just clear with a G0 move.  I'm running LinuxCNC 2.8.2-1-g6a3d0a434.  

I've never had issues using nativecam in the past.  I pulled it in as a deb and used dpkg -i to install it.  I ran the install with
nativecam -i mymill.ini -c mill  (something like that).

I tried running my program without the block delete, got the reminder, and then I keep getting the non-negative Q-word error. 

Turning off the auto-load of ncam.ngc and loading another known working program doesn't clear it.  Every program loaded afterwards pulls up the same error, just a different filename. 

It appears that by doing a G0 G53 X14 the error cleared.  I thought I was stuck with the error forever, but it seemed somehow the G0 "kicked" something.

Thank you!

That's the kicker -- The indicated file doesn't have an M61. It's as if the interpreter has some stale state or code stuck in it after the error is triggered. If I figure out a way to force it to happen, I'll post the info for debugging. ANY program I attempt to load that has worked previously fails with the same error on "line 0". Even ones without an M61 line. Maybe I'll have to set up obs or something to record the screen so I can figure out what has caused it. Once I did the G0 move or restarted linuxcnc everything is fine until something bad happens in nativecam.

Andy -- Thank you for looking into this more. 
The only occurrences of M61 in my stuff are below.

my_LinuxCNC_machine2.ini:MDI_COMMAND = M66 E0 M61 Q[#5399] G43

I use M61 in my manual tool change button pyvcp.  When I push the manual button it takes the results from M66 and passes them to M61 to change the tool to the number I put in my spinbox.  I've used it for years and it only has positive values ever. 

I also have a script that I run to adjust my fixture offsets.  But clearly, it passes Q0 to change to tool 0.  I have been using G38.2 seeks to probe recently which I think is irrelevant.  Making brackets for my prox switches is why I was using NCAM and found this weird behavior. 

store_home_adjust_g54.sh:axis-remote --mdi "M61 Q0"
store_home_adjust_g54.sh:axis-remote --mdi "M61 Q0"

 

Thanks, Andy.  I'll give that a try. I had dismissed this as being a potential source of the problem because it only fires off with the button press. I particularly like the guarantee of order of operations. 

I know this is a older post, but I am experimenting a really similar issue.

In my case, I get this when I manually use use a M61 via MDI before loading a file. The file preview fail to be generated but the file load correctly. The error is generated when I load any file until I do a M6 tool change via MDI.

The g-code I load does not contain any M61. The message I get is:

Near line 1 of ...
Need non-negative Q-word to specify tool number with M61