I have had similar problems for years with my Force 10 stove which I bought new. Unfortunately I discovered the problem after heading out on a long overseas passage
Interestingly, same problem showed up when I re-installed the stove on a new to me boat.
If the propane solenoid is left on and pressure applied the stove will start immediately on the first try (even after a few days -- oops...)
If the propane solenoid is turned off after use and then turned back on:
If the stove burner has been run in the last 24 hours it runs perfectly
If the stove burner has been run in the last 48 hours it will light up within a couple of seconds, perhaps with a bit of sputtering
If the stove has not been run for several days then it may take almost a minute to get the burner to light. Sometimes in this case the propane sensor will go off although only if more than 45 seconds or so.
However, some new information. If trying different burners it always sputters and is difficult to start after having been off for a week or more.
On the other hand, if I try to start the oven
first, it never results in the propane sensor going off AND while it may take as much as 30 seconds to light, when it does it is an immediate clean start.
I suspect that air is getting into the system through the oven
burner when the propane is off and then some of this air mixes with the propane when the system is turned on.
Odd behavior in any event.