Hi Brian, you are describing an intermittent circuit. It is either on the signal wire from the RPi to the level converter or the converted signal wire from the level converter to the LED string, or on the ground circuit, remember that both the RPi and the LED string must share the same ground level for the LED's to react properly.

This is not an uncommon issue. In fact if you look through the posts you'll see many such concerns. In most cases, moving the jumper wires to another port on the breadboard takes care of it, and in some cases it took soldering to eliminate the intermittent issue. Its frustrating but on insurmountable. 

Post a picture of you wiring setup if you think we can help by looking at it. - Mark

Ok will go back and check.  The frustrating part is it worked perfectly when half done.

In progress project photo.

Hey, that looks great. I really like your legend! - Mark

So I moved a few things to different pins on breadboard.  Wired as the diagram.  Was working better but got an occasional flash.  I rebooted and now it is flashing lights randomly singles, in groups, all.  Now nothing working properly.

While the problem is occurring, wiggle one wire at a time to see if you can figure out which wire is intermittent. Also, while rare I've had jumper wires making and breaking contact, so keep an eye open for that possibility. Adafruit.com sells solderable breadboards that are inexpensive. Check out; https://www.adafruit.com/product/1609?gclid=Cj0KCQiA4feBBhC9ARIsABp_nbWSe8-70AAfkY_vunmdWVosnt6hFsqwC0T2kQC6_0Jq7UyBSn8gOmEaAhHNEALw_wcB

This will really help eliminate intermittent connections. - Mark

I'm now getting essentially zero response from the LEDs.  I moved things on the board multiple times, replaced jumpers all with no result.  The map is pretty much dead.  I'll get one or two LED that will come on occasionally.  No response to "all on" and no call up of individual LEDs.  I even went back and reflashed the card and reloaded everything.  Still nothing.  Wiggling wires = nothing.  Could the little converter have gone bad?

That is possible if it was wired incorrectly at some point. Post a picture of the breadboard et al and we'll look to ensure that its wired properly. - Mark

Here are some photos.

I just have the led light strings plugged together.  There are also bare ends at beginning and end of each string for power and ground.  Do I need to connect those together?  Wouldn't think that would be the problem since the map was essentially working at one point. 

Also I did cut the last 9 lights off the second string and soldered in about 12" of wire in order to extend the string to some outlying points.  But again don't know that this is a problem since things were working for a short period of time.

Brian, your wiring looks correct. I couldn't tell, but I'm assuming the level converter chip is oriented with the semi-circle locator facing to the left (in the pictures).

So assuming this is all correct, could it be that the power supply isn't big enough to handle 100 LED's? If you disconnect the 2nd string will they light up correctly?

There have been some builders who have mentioned that they needed to feed power to both ends of their strings. The signal wire needs to be connected to the front end of the string. In fact there are arrows that point in the direction the signal needs to be fed into the string. The arrows are on the small circuit boards connected to each LED. So you might double check that too.

Sorry for the hassles, but you will find it. We'll help as much as possible. - Mark

The semi-circle is on the left.  LEDSs signal is being fed correctly according to the arrows. Power supply is 5V 8A 40W.  I disconnected the second string and they light but randomly and can't control them in any way.

I ordered a new converter chip and solderable breadboard. 

How would I go about powering the other end of my LED string?  Where should I pull the power from?

First ensure you have a large enough power supply to do the job. The one listed in the build procedure will easily drive 2 strings of LED's but if you are using a smaller one, then you may want to upgrade the power supply.

To answer your question, you would be running 2 more wires from your power supply to the other end of the string. There should be wires with a female connector coming off the other end that you can connect the power supply to the +5v and Grd wires. So the same power supply will be supplying power to each end of the strings of LED's. Be sure to not connect the signal wire up to both ends. It just connects to the one location you have already.

Let me know if this is unclear and I'll draw out the schematic. - Mark