To summarize, for performance reasons, all regular strings should be pointed to by an odd address, so BaCon can identify string- and buffer length. The last line of your code assigns a pointer address back to a string, and BaCon now takes the bytes just before that position as parameters for these lengths. This causes an undefined large range to handle.
As a quick woraround, you can change the last line of your code as follows:
However, note that BaCon now has a very strong delimited string engine of which the API was proposed by forum member vovchik.
To achieve your results, the following code will do the same:
sendstr$ = "timeout60:myapp" IF NOT(TALLY(sendstr$, ":")) THEN END field1$ = TOKEN$(sendstr$, 1, ":") field2$ = TOKEN$(sendstr$, 2, ":")